BETA — measurements and names under active refinement. Seen a sign, a gate, or a better name? Submit an update no account needed · photos welcome via GitHub

UK Climb Survey

How steep is that hill, really? It depends how far you measure: the same hill can honestly be 32% over 2 m and 25% over 100 m at once. So every number here states the distance it was measured over, computed from Britain’s public laser height surveys in a way anyone can re-check. Wales so far, plus a first handful of English climbs — the full England survey is running now. How to read these numbers →

257 climbs published · 37 km of climbing between them · steepest 25 m: 32.6% (Ffordd Pen Llech) · longest: 9.4 km (Lawnt to Tir Mostyn) · 25 counties

What it takes to be included: 5,918 candidate roads were measured in Wales. A road gets a page if at least one of these is true:

a person chose it: the survey’s hand-curated starting set, and the human-reviewed trunk-road selection;
it matches a climb already documented elsewhere — a book, a championship, a race route, an article (the Matches column);
25 continuous metres at 20% or steeper, where the measurement is clean: minimal tree cover on that stretch and no caveats on the value;
25 continuous metres at 26% or steeper — here caveated measurements are allowed (tree cover is common on the steepest lanes), but the numbers must pass plausibility checks that reject wall and terrain-model artifacts;
at least 1.5 km at 10% or steeper overall;
total rise among the 30 biggest in the survey.

One is enough, and most pages come through the steepness doors — in the current Welsh discovery set: 80 climbs qualify under the 26% tier, 66 under the clean 20% tier, 19 by top-30 rise, 13 by the 1.5 km rule (8 on that rule alone), with the rest matched or curated. Most of the 5,918 measured roads met none of these and have no page.

Steepest 10 m

#	Climb	Max	Length	Overall	Confidence
1	Rhiw Syr Dafydd	≈40%	125 m	20.6%	Good
2	Sennybridge to Yr Allt^°	40%	1412 m	3.9%	Good
3	Mountain Road	≈40%	514 m	10.4%	Good
4	Yr Allt	≈37%	537 m	10.5%	Good
5	Yr Allt	≈37%	562 m	9.0%	Good
6	Allt y Badi (south side)	≈37%	2707 m	9.0%	Good
7	Fforest Road	≈37%	925 m	12.5%	Good
8	Bethlehem to Carn Powell^°	≈37%	3549 m	5.7%	Good
9	Llandeilo Road	≈37%	2628 m	4.9%	Good
10	Cwm Sŷch to Cwm Dyfnant	≈36%	2681 m	6.6%	Good
11	Ffordd Pen Llech	≈36%	237 m	17.2%	Good
12	Hafod Lane	≈36%	2898 m	4.5%	Good
13	Cwm Llwynau to Cwm Cnyw^°	≈36%	1135 m	6.2%	Good
14	Dyffryn Conwy to Mynydd Cauedig	≈36%	1784 m	9.9%	Good
15	Lane near Pont-Tyweli^°	≈35%	1898 m	5.5%	Good

≈ measured under tree canopy or near a structure at this window — the value stands but is less certain — the flag does not say whether the true value is higher or lower. Each climb page details what was flagged and why.

° provisional auto-generated name — details on the climb page.

Steepest 25 m

#	Climb	Max	Length	Overall	Confidence
1	Ffordd Pen Llech	≈32.6%	237 m	17.2%	Good
2	Allt y Badi (south side)	≈31.7%	2707 m	9.0%	Good
3	Mountain Road	≈31.4%	514 m	10.4%	Good
4	Route Des Alpes	≈31.0%	2169 m	6.8%	Good
5	Lane near Cellan^°	≈30.1%	2094 m	5.9%	Good
6	Heol Feurig	≈30.0%	284 m	11.5%	Good
7	Llandeilo Road	≈29.8%	2628 m	4.9%	Good
8	Bethlehem to Carn Powell^°	≈29.6%	3549 m	5.7%	Good
9	Coronation Street	29.6%	307 m	11.4%	High
10	Rhiw Syr Dafydd	≈29.6%	125 m	20.6%	Good
11	Sennybridge to Yr Allt^°	≈29.5%	1412 m	3.9%	Good
12	Parc-Seymour to Castell-prin	≈29.5%	478 m	10.1%	Good
13	Lane near Blaenllechau^°	≈29.4%	447 m	6.7%	Good
14	Pant Du	≈29.4%	825 m	12.3%	Good
15	Dinas Oleu Lane	≈29.4%	198 m	21.5%	Good

° provisional auto-generated name — details on the climb page.

Steepest 50 m

#	Climb	Max	Length	Overall	Confidence
1	Ffordd Pen Llech	≈29.8%	237 m	17.2%	Good
2	Mountain Road	≈28.5%	514 m	10.4%	Good
3	Llanguicke Road	≈28.4%	1172 m	13.3%	Good
4	Ffordd Bryn Fran	≈27.9%	2943 m	9.9%	Good
5	Dinas Oleu Lane	≈27.8%	198 m	21.5%	Good
6	Ffordd Llwyn Du	27.4%	1494 m	12.2%	Good
7	Pound Lane	≈27.0%	1461 m	10.5%	Good
8	Lane near Fron^°	≈27.0%	492 m	18.1%	Good
9	Cefn Llan	≈26.6%	218 m	19.4%	Good
10	Heol Feurig	≈26.5%	284 m	11.5%	Good
11	Bryncethin Road	≈26.5%	1635 m	8.9%	Good
12	Cwrdy Lane	≈26.4%	1757 m	9.0%	Good
13	Coronation Street	26.3%	307 m	11.4%	High
14	Clifton Hill	26.2%	141 m	23.9%	High
15	Cwm Ffrydlan to Bryn Mawr^°	≈26.2%	3364 m	5.8%	Good

° provisional auto-generated name — details on the climb page.

Steepest 100 m

#	Climb	Max	Length	Overall	Confidence
1	Ffordd Pen Llech	≈26.5%	237 m	17.2%	Good
2	Dinas Oleu Lane	≈25.3%	198 m	21.5%	Good
3	Cefn Llan	≈25.1%	218 m	19.4%	Good
4	Clifton Hill	24.9%	141 m	23.9%	High
5	Mount Road	≈24.4%	825 m	11.5%	Good
6	Ffordd Bryn Fran	≈24.4%	2943 m	9.9%	Good
7	Pant Du	≈24.3%	825 m	12.3%	Good
8	Vine Row	≈24.1%	667 m	12.3%	Good
9	Ffordd Llwyn Du	24.0%	1494 m	12.2%	Good
10	Partrishow Hill to Partrishow^°	≈23.9%	2447 m	6.3%	Good
11	Pound Lane	≈23.9%	1461 m	10.5%	Good
12	Cwrdy Lane	≈23.8%	1757 m	9.0%	Good
13	Allt y Badi (south side)	≈23.6%	2707 m	9.0%	Good
14	Lane near Glyn Ceiriog^°	≈23.5%	522 m	11.4%	Good
15	Lower Harper's Road	≈23.4%	1502 m	7.6%	Good

° provisional auto-generated name — details on the climb page.

Largest net rise

#	Climb	Net rise	Total ascent	Length	Overall	Confidence
1	Llanellen to Cefn y Galchen^°	452 m	482 m	5964 m	7.6%	Good
2	Lawnt to Tir Mostyn^°	331 m	430 m	9367 m	3.5%	High
3	Dardy to Blaen Onneu^°	328 m	361 m	6272 m	5.2%	Good
4	Milltir Gerrig	325 m	337 m	5940 m	5.5%	Good
5	Cyffredyn to Blaen Onneu^°	323 m	339 m	4794 m	6.7%	Good
6	Hardknott Pass	315 m	318 m	3119 m	10.1%	Good
7	Erwyd to Llangynog	308 m	345 m	5937 m	5.2%	Good
8	Rhigos Road	305 m	308 m	6004 m	5.1%	High
9	Welsh Harp Hollow	304 m	315 m	3695 m	8.2%	Good
10	Ffordd Bryn Fran	292 m	312 m	2943 m	9.9%	Good
11	Creigiau'r Llyn to Foel Y Groes^°	286 m	375 m	6349 m	4.5%	Good
12	Llanybydder to Mynydd Llanybyther^°	286 m	307 m	6003 m	4.8%	Good
13	Glyndyfrdwy to Moel Morfydd^°	279 m	311 m	3629 m	7.7%	Good
14	Nant-y-Rhiw to Moel Trefriw^°	279 m	310 m	4096 m	6.8%	Good
15	Barber's Hill	276 m	383 m	6052 m	4.6%	Good

° provisional auto-generated name — details on the climb page.

Net rise is the endpoint elevation difference (what overall gradient is computed from); total ascent counts every metre climbed, including dips regained. Rankings include high- and good-confidence measurements only (how confidence works).

Provisional discoveries — awaiting review

These trip our own plausibility checks (confidence: needs confirmation): the numbers below may be terrain-model artifacts and are NOT ranked until a human review — or your local knowledge — settles them. Steepest first at 10 m.

#	Climb	Max 10 m	Length	Confidence
1	Berwyn to Geraint Hill^°	42%	3790 m	Needs confirmation
2	Llangollen to Blaen-Bache Dingle^°	41%	2680 m	Needs confirmation
3	Melin-y-coed to Pant-y-maes^°	38%	2452 m	Needs confirmation
4	Ffordd-las to Hay Bluff^°	35%	6927 m	Needs confirmation
5	Lon Bribwll	34%	635 m	Needs confirmation
6	Rhyd-y-gwin to Tor Clawdd^°	34%	3579 m	Needs confirmation
7	Llwynmawr to Bedwlwyn^°	33%	1808 m	Needs confirmation
8	The Conduit	32%	743 m	Needs confirmation
9	Bwlch Esgair Gelli	32%	2505 m	Needs confirmation
10	Mountain Road	31%	3884 m	Needs confirmation

° provisional auto-generated name — details on the climb page.

…and 18 more in the catalogue below (filter: awaiting review).

All climbs (257)

Climb	Area	Matches	Shape	Length	Net rise	Overall	Max 25 m	Confidence
Aberarth to Graig Ddu		—	sustained	1967 m	98 m	5.0%	12.9%	High
Aberdyfi to Ffridd Cefn-isaf^°	near Aberdyfi · Gwynedd	—	sustained	1610 m	181 m	11.2%	20.9%	High
Aberedw to Pontsioni^°	near Aberedw · Powys	—	sustained	654 m	93 m	14.3%	26.5%	Good
Aberffrwd Hill	near Aberffrwd · Ceredigion	—	sustained	2372 m	237 m	10.0%	≈26.1%	Good
Adams Street to Cerrig yr Hafan		—	sustained	8383 m	380 m	4.5%	14.5%	Needs confirmation
Allt Bron Philip	near Llanddona · Sir Ynys Mon / Isle of Anglesey	—	sustained	1442 m	139 m	9.6%	≈26.2%	Good
Allt Goch Fawr	near Nant Meigan · Sir Ynys Mon / Isle of Anglesey	tag: 25% (2026)	stepped	1266 m	83 m	6.5%	≈15.0%	Needs confirmation
Allt y Badi (south side)	near Glyn Ceiriog · Wrecsam / Wrexham	tag: 25% (2026)	stepped	2707 m	243 m	9.0%	≈31.7%	Good
Aston Expressway	near Ewloe · Sir y Fflint / Flintshire	Wikipedia¹	sustained	747 m	32 m	4.3%	11.7%	Needs confirmation
Bank Road	near Matlock · Derbyshire	100 Climbs², National HC³, Wikipedia¹	sustained	530 m	57 m	10.7%	15.5%	High
Barber's Hill	near The Dingle · Sir Ddinbych / Denbighshire	National HC³	sustained	6052 m	276 m	4.6%	≈21.7%	Good
Bedwellty Road	near Aberbargoed · Caerffili / Caerphilly	—	sustained	1891 m	144 m	7.6%	21.0%	High
Berwyn to Geraint Hill^°	near The Dingle · Sir Ddinbych / Denbighshire	—	sustained	3790 m	286 m	7.5%	≈20.9%	Needs confirmation
Bethlehem to Carn Powell^°	near Capel Dingle · Sir Gaerfyrddin / Carmarthenshire	—	sustained	3549 m	201 m	5.7%	≈29.6%	Good
Bettws Gwerfil Goch to Pen Hafoty-Foel^°	near Bettws Gwerfil Goch · Sir Ddinbych / Denbighshire	—	sustained	1608 m	97 m	6.0%	≈27.2%	Good
Bevan Avenue	near Mochdre · Conwy	—	stepped	660 m	61 m	9.2%	23.0%	High
Blackvein Mountain Road	near Glenside · Caerffili / Caerphilly	—	sustained	1688 m	176 m	10.4%	≈25.9%	Good
Blaenavon Road		—	sustained	4320 m	367 m	8.5%	≈14.5%	Needs confirmation
Boughrood to Trewern Hill^°	near Llanstephan · Powys	—	sustained	4401 m	228 m	5.2%	21.9%	High
Brace Avenue	near Blaenau Gwent · Blaenau Gwent	—	sustained	937 m	60 m	6.4%	21.1%	High
Brongwyn to Capel Tygwydd^°	near Troed-y-rhiw-Siôn · Ceredigion	—	stepped	1288 m	64 m	5.0%	≈26.0%	Good
Bryn Dolwen to Tyddyn^°	near Cwm y Glog · Powys	—	sustained	1499 m	85 m	5.7%	20.2%	High
Bryn Rhyd-yr-Arian to Mynydd Tryfan^°	near Dyffryn Aled · Conwy	—	sustained	2925 m	148 m	5.1%	≈29.0%	Good
Bryn Road	near Pen-Rhiw-fawr · Castell-nedd Port Talbot / Neath Port Talbot	—	sustained	395 m	49 m	12.4%	21.8%	High
Bryncethin Road	near Cwm Garnant · Castell-nedd Port Talbot / Neath Port Talbot	—	sustained	1635 m	146 m	8.9%	≈28.2%	Good
Brynllys to Bwlch Oerddrws^°	near Cwm Cerist · Gwynedd	Wikipedia¹	stepped	5159 m	248 m	4.8%	16.5%	High
Bush Road	near Miskin · Rhondda Cynon Taf	—	sustained	466 m	60 m	12.8%	22.0%	High
Bwlch Esgair Gelli		—	sustained	2505 m	164 m	6.5%	23.7%	Needs confirmation
Bwlch Penbarras	near Llanbedr-Dyffryn-Clwyd · Sir Ddinbych / Denbighshire	100 Climbs², National HC³, Wikipedia¹	sustained	2324 m	260 m	11.2%	≈24.4%	Needs confirmation
Bwlch Sychnant	near Capelulo · Conwy	Wikipedia¹, Warren app⁴	sustained	743 m	93 m	12.5%	≈15.0%	Good
Bwlch y Groes	near Cwm Cerddin · Gwynedd	Wikipedia¹, 100 Climbs²	sustained	1214 m	188 m	15.5%	23.8%	High
Bwlch-y-Clawdd Road	near Cwm Dâr · Rhondda Cynon Taf	100 Climbs²	sustained	4804 m	270 m	5.6%	8.9%	High
Cairo Street	near Dinas · Rhondda Cynon Taf	—	sustained	358 m	34 m	9.5%	22.3%	High
Capel Bangor to Pant-y-crug	near Pant-y-crûg · Ceredigion	—	sustained	1389 m	145 m	10.5%	≈21.0%	Good
Cefn Llan	near Cwmpadarn · Ceredigion	sign: 32% (2025)	sustained	218 m	42 m	19.4%	≈27.4%	Good
Cefn Vron Hill to Bryn^°	near Anchor · Shropshire	—	sustained	649 m	50 m	7.7%	20.7%	High
Ceunant Gorddinan to Ffridd-y-Bwlch		—	sustained	2266 m	130 m	5.7%	11.6%	High
Charles Street	near Trealaw · Rhondda Cynon Taf	—	sustained	915 m	97 m	10.6%	20.7%	High
Clifton Hill	near Abertawe · Abertawe / Swansea	—	sustained	141 m	34 m	23.9%	27.8%	High
Clynnog Fawr to Bwlch Mawr^°	near Capel Uchaf · Gwynedd	—	stepped	3170 m	192 m	6.1%	22.8%	High
Commin Road	near Aberbargoed · Caerffili / Caerphilly	—	stepped	1344 m	119 m	8.9%	21.0%	High
Commins Coch to Darowen^°	near Darowen · Powys	—	sustained	2468 m	119 m	4.8%	26.5%	Good
Constitution Hill	near Mount Pleasant · Abertawe / Swansea	Wikipedia¹, 100 Climbs²	sustained	348 m	61 m	17.4%	21.9%	High
Coronation Street	near Wyndham · Pen-y-bont ar Ogwr / Bridgend	—	stepped	307 m	35 m	11.4%	29.6%	High
Creigiau'r Llyn to Foel Y Groes^°	near Cwm Eunant · Powys	—	sustained	6349 m	286 m	4.5%	≈19.7%	Good
Crimea Pass (Bwlch y Gorddinan)	near Tal-y-waenydd · Gwynedd	Wikipedia¹, Warren app⁴	sustained	2705 m	260 m	9.6%	≈18.4%	Needs confirmation
Crossway to Tyn Green Castle^°	near Crossway · Powys	—	stepped	2848 m	112 m	3.9%	22.1%	High
Cwm Dulais to Cwm Ysgiach^°	near Cwm Dulais · Abertawe / Swansea	—	stepped	1908 m	39 m	2.0%	27.1%	High
Cwm Ffrydlan to Bryn Mawr^°	near Cwm Esgaireira · Powys	—	stepped	3364 m	193 m	5.8%	≈27.0%	Good
Cwm Llwynau to Cwm Cnyw^°	near Cwm Llwynau · Torfaen	—	stepped	1135 m	70 m	6.2%	≈26.8%	Good
Cwm Sŷch to Cwm Dyfnant		—	sustained	2681 m	177 m	6.6%	≈26.4%	Good
Cwm Wern-ddu to Llanfihangel-y-Creuddyn^°	near Llanfihangel-y-Creuddyn · Ceredigion	—	sustained	1549 m	98 m	6.3%	≈20.1%	Good
Cwm y Gâth to Bryn-y-Fedwen		—	sustained	8271 m	456 m	5.5%	22.6%	Needs confirmation
Cwm-hirblyg to Glyn Llydan^°	near Glyn Llydan · Sir Gaerfyrddin / Carmarthenshire	—	sustained	2890 m	96 m	3.3%	≈26.7%	Good
Cwm-hirblyg to Pen Rhiw-Wen^°	near Cwm Nant-dywyll · Sir Gaerfyrddin / Carmarthenshire	—	sustained	5282 m	272 m	5.2%	18.7%	Good
Cwrdy Lane	near Penyrheol · Torfaen	—	stepped	1757 m	158 m	9.0%	≈28.7%	Good
Cyffredyn to Blaen Onneu^°	near Cwm Cleisfer · Powys	—	sustained	4794 m	323 m	6.7%	16.2%	Good
Dardy to Blaen Onneu^°	near Cwm Onnau · Powys	—	sustained	6272 m	328 m	5.2%	≈23.2%	Good
Derwen Lane	near Penrhyn-side · Conwy	—	stepped	1188 m	78 m	6.5%	27.2%	High
Devil's Staircase	near Coed Nant-yr-hwch · Powys	Another 100⁵, 100 Climbs²	sustained	841 m	111 m	13.2%	24.5%	High
Devil's Staircase (west side)	near Coed Nant-yr-hwch · Powys	tag: 25% (2026)	stepped	2348 m	181 m	7.7%	22.3%	High
Dinas Oleu Lane	near Abermaw · Gwynedd	—	sustained	198 m	43 m	21.5%	≈29.4%	Good
Discoed to Upper Dunn's Plantation^°	near Thorn · Powys	—	stepped	2144 m	164 m	7.7%	≈26.2%	Good
Dolhendre to Carndochan^°	near Rhosdylluan · Gwynedd	—	sustained	642 m	53 m	8.3%	≈26.5%	Good
Duffield's Lane	near Upper Redbrook · Sir Fynwy / Monmouthshire	—	sustained	993 m	102 m	10.3%	≈26.0%	Good
Dyffryn Conwy to Mynydd Cauedig		—	sustained	1784 m	176 m	9.9%	≈26.8%	Good
Eisingrug to Moel y Geifr^°	near Eisingrug · Gwynedd	—	sustained	2149 m	217 m	10.1%	≈22.0%	Good
Erwyd to Llangynog		—	sustained	5937 m	308 m	5.2%	≈18.9%	Good
Felindre to Cwm Hyfryd^°	near Cwmpengraig · Sir Gaerfyrddin / Carmarthenshire	—	sustained	5214 m	262 m	5.0%	≈17.6%	Good
Ffordd Bryn Fran	near Pentre'r Felin · Conwy	—	sustained	2943 m	292 m	9.9%	≈28.1%	Good
Ffordd Llwyn Du	near Pentre'r Felin · Conwy	—	sustained	1494 m	182 m	12.2%	28.3%	Good
Ffordd Pen Llech	near Harlech · Gwynedd	Guinness⁶, Wikipedia¹, 100 Climbs²	sustained	237 m	41 m	17.2%	≈32.6%	Good
Ffordd Rhiwlas		—	stepped	2601 m	159 m	6.1%	≈26.5%	Good
Ffordd y Graig	near Trebannws · Castell-nedd Port Talbot / Neath Port Talbot	—	sustained	1632 m	173 m	10.6%	≈26.2%	Good
Ffordd-las to Hay Bluff^°	near Tregoyd · Powys	—	sustained	6927 m	294 m	4.2%	≈28.7%	Needs confirmation
Fforest Road	near Caegarw · Rhondda Cynon Taf	—	sustained	925 m	115 m	12.5%	≈26.8%	Good
Garth to Cwmsymlog^°	near Pen-rhiw-newydd · Ceredigion	—	sustained	4880 m	273 m	5.6%	18.5%	Needs confirmation
Georges Delight	near Gaer-fawr · Sir Fynwy / Monmouthshire	—	stepped	2215 m	162 m	7.3%	≈26.4%	Good
Gladestry to Hengoed		—	stepped	1821 m	100 m	5.5%	≈26.5%	Needs confirmation
Glamorgan Street	near Penrhiwceiber · Rhondda Cynon Taf	—	sustained	1148 m	113 m	9.8%	21.7%	High
Glyndyfrdwy to Moel Morfydd^°	near Glyndyfrdwy · Sir Ddinbych / Denbighshire	—	stepped	3629 m	279 m	7.7%	25.5%	Good
Govilon to Gilwern Hill^°	near Cwm Llanwenarth · Sir Fynwy / Monmouthshire	—	sustained	1788 m	187 m	10.5%	≈22.2%	Good
Greenfield Place	near Middle Coedcae · Torfaen	—	sustained	600 m	48 m	7.9%	22.3%	High
Groeslon-waun to Cefn Du^°	near Groeslon · Gwynedd	—	stepped	1714 m	98 m	5.7%	26.2%	High
Gully to Pen y Ffynnon^°	near Gully · Powys	—	stepped	1677 m	125 m	7.5%	27.5%	High
Gwyddelwern to Betws Gwerful Goch		—	sustained	3132 m	164 m	5.3%	≈26.2%	Good
Hafod Lane	near Trehafod · Rhondda Cynon Taf	—	sustained	2898 m	130 m	4.5%	≈27.3%	Good
Hafod-fan Road	near Six Bells · Blaenau Gwent	—	sustained	181 m	31 m	17.0%	20.4%	High
Halswell Street	near Tyntetown · Rhondda Cynon Taf	—	sustained	163 m	21 m	12.7%	20.7%	High
Hardknott Pass		100 Climbs², Wikipedia¹	sustained	3119 m	315 m	10.1%	25.9%	Good
Heartsease to Stanage Park^°	near Heartsease · Powys	—	sustained	894 m	70 m	7.9%	20.2%	High
Hen Ffordd	near Bwlch · Powys	—	sustained	419 m	40 m	9.4%	≈21.0%	Good
Hendre Owen Road	near Duffryn · Castell-nedd Port Talbot / Neath Port Talbot	—	sustained	309 m	46 m	15.0%	23.1%	High
Henllys to Nant Carn^°	near Henllys · Torfaen	—	sustained	1553 m	187 m	12.1%	≈25.4%	Good
Heol Calch	near Cwm Gored · Powys	—	stepped	925 m	86 m	9.3%	≈26.0%	Good
Heol Feurig	near Dolgellau · Gwynedd	—	stepped	284 m	33 m	11.5%	≈30.0%	Good
Heol Lan		—	stepped	2788 m	142 m	5.1%	≈26.3%	Good
Heol y Banc	near Llygadywawr · Sir Gaerfyrddin / Carmarthenshire	—	sustained	1670 m	164 m	9.8%	21.9%	High
High Meadow to Hafodyrynys^°	near Cwm Hafod-fach · Caerffili / Caerphilly	—	stepped	4325 m	266 m	6.1%	≈24.0%	Good
Hill Road	near Pontlottyn · Caerffili / Caerphilly	—	stepped	1187 m	114 m	9.6%	21.6%	High
Hill Street	near Cwm Ysgwydd-gwyn · Caerffili / Caerphilly	—	sustained	1697 m	146 m	8.6%	27.9%	High
Hill Terrace	near Carreg yr Eos · Sir Benfro / Pembrokeshire	—	sustained	589 m	58 m	9.8%	15.0%	High
Hillside		—	sustained	801 m	132 m	16.5%	24.6%	High
Horseshoe Pass		Nat HC 1971³, National HC³, Wikipedia¹, 100 Climbs²	sustained	4543 m	276 m	6.1%	≈14.4%	Good
Lane near Abercych^°	near Abercych · Sir Benfro / Pembrokeshire	—	stepped	684 m	73 m	10.6%	≈26.3%	Good
Lane near Betws-y-coed	near Betws-y-Coed · Conwy	tag: 20% (2026)	sustained	1263 m	162 m	12.8%	≈21.6%	Good
Lane near Blaen-y-Glyn	near Bannau Brycheiniog · Powys	tag: 20% (2026)	sustained	1515 m	180 m	11.8%	≈19.7%	Good
Lane near Blaenllechau^°	near Blaenllechau · Rhondda Cynon Taf	—	stepped	447 m	30 m	6.7%	≈29.4%	Good
Lane near Cellan^°	near Cellan · Ceredigion	—	stepped	2094 m	124 m	5.9%	≈30.1%	Good
Lane near Ceunant		—	sustained	991 m	86 m	8.7%	≈26.4%	Good
Lane near Cwrt	near Cwm Ffernol · Gwynedd	tag: 20% (2026)	sustained	1015 m	94 m	9.2%	24.4%	High
Lane near Dolgellau^°	near Dolgellau · Gwynedd	—	sustained	234 m	35 m	15.1%	20.3%	High
Lane near Fron^°	near Fron · Powys	—	sustained	492 m	89 m	18.1%	≈29.3%	Good
Lane near Garndolbenmaen^°	near Garndolbenmaen · Gwynedd	—	stepped	722 m	65 m	9.0%	20.6%	High
Lane near Gilfach^°	near Gilfach · Caerffili / Caerphilly	—	stepped	352 m	28 m	7.8%	20.7%	High
Lane near Glascoed^°	near Glascoed · Powys	—	stepped	1360 m	101 m	7.5%	25.2%	High
Lane near Glyn Ceiriog^°	near Glyn Ceiriog · Wrecsam / Wrexham	—	stepped	522 m	60 m	11.4%	≈27.2%	Good
Lane near Glyn Ceiriog^°	near Glyn Ceiriog · Wrecsam / Wrexham	—	sustained	1051 m	87 m	8.3%	≈27.2%	Needs confirmation
Lane near Glyn Saer^°	near Cwm-bychan · Sir Gaerfyrddin / Carmarthenshire	—	stepped	7043 m	150 m	2.1%	11.7%	Needs confirmation
Lane near Kilgwrrwg Common^°	near Kilgwrrwg · Sir Fynwy / Monmouthshire	—	stepped	1472 m	117 m	7.9%	≈27.5%	Good
Lane near Leighton	near Pentre · Powys	tag: 20% (2026)	sustained	646 m	70 m	10.9%	≈22.8%	Good
Lane near Llanarmon Mynydd Mawr	near Llanrhaeadr-ym-Mochnant · Powys	tag: 20% (2026)	sustained	762 m	85 m	11.1%	≈26.8%	Good
Lane near Llanddeusant^°	near Llanddeusant · Sir Gaerfyrddin / Carmarthenshire	—	sustained	499 m	66 m	13.2%	≈27.4%	Good
Lane near Llanedi^°	near Llanedi · Sir Gaerfyrddin / Carmarthenshire	—	stepped	1275 m	66 m	5.2%	20.3%	High
Lane near Llanfair Talhaearn^°	near Llanfair Talhaiarn · Conwy	—	sustained	1627 m	141 m	8.6%	20.4%	High
Lane near Llangadfan^°	near Llangadfan · Powys	—	sustained	546 m	56 m	10.2%	≈27.3%	Good
Lane near Llanglydwen^°	near Llanglydwen · Sir Gaerfyrddin / Carmarthenshire	—	sustained	1839 m	96 m	5.2%	20.3%	High
Lane near Llanybri^°	near Llanybri · Sir Gaerfyrddin / Carmarthenshire	—	sustained	879 m	93 m	10.5%	≈26.4%	Good
Lane near Llanystumdwy^°	near Llanystumdwy · Gwynedd	—	stepped	556 m	36 m	6.4%	≈27.0%	Good
Lane near Maen-Offeren^°	near Maen-Offeren · Gwynedd	—	sustained	225 m	29 m	13.1%	25.3%	High
Lane near Maenan^°	near Maenan · Conwy	—	sustained	1027 m	138 m	13.5%	≈27.5%	Good
Lane near Miskin^°	near Miskin · Rhondda Cynon Taf	—	stepped	752 m	70 m	9.3%	22.0%	High
Lane near Miskin^°	near Miskin · Rhondda Cynon Taf	—	sustained	315 m	47 m	14.9%	21.0%	High
Lane near Pont-Tyweli^°	near Pont-Tyweli · Sir Gaerfyrddin / Carmarthenshire	—	sustained	1898 m	104 m	5.5%	≈23.9%	Good
Lane near Price Town^°	near Price Town · Pen-y-bont ar Ogwr / Bridgend	—	sustained	432 m	46 m	10.6%	22.9%	High
Lane near Rhyd-Meirionnydd		tag: 25%	sustained	4090 m	116 m	2.8%	13.9%	Good
Lane near Stanleytown^°	near Stanleytown · Rhondda Cynon Taf	—	sustained	164 m	27 m	16.1%	28.4%	High
Lane near Stepaside^°	near Stepaside · Powys	—	sustained	1727 m	112 m	6.5%	≈26.3%	Good
Lane near Ton Pentre^°	near Ton Pentre · Rhondda Cynon Taf	—	sustained	314 m	40 m	12.6%	≈28.5%	Good
Lane near Trealaw^°	near Trealaw · Rhondda Cynon Taf	—	stepped	253 m	25 m	9.9%	≈24.5%	Good
Lane near Ty'n-y-groes^°	near Ty'n-y-groes · Conwy	—	stepped	957 m	48 m	5.0%	≈26.2%	Good
Lane near Wernffrwd^°	near Wernffrwd · Abertawe / Swansea	—	sustained	1264 m	81 m	6.4%	22.0%	High
Lane near Whitesands Bay^°	near Whitesands Bay · Sir Benfro / Pembrokeshire	—	sustained	610 m	48 m	7.9%	22.1%	Good
Lane near Ystradfellte^°	near Ystradfellte · Powys	—	stepped	2317 m	79 m	3.4%	21.0%	High
Lawnt to Tir Mostyn^°	near Soar · Sir Ddinbych / Denbighshire	—	sustained	9367 m	331 m	3.5%	17.9%	High
Lewis Street	near Prospect Place · Torfaen	—	stepped	1483 m	87 m	5.9%	23.2%	High
Llanarth to Synod Inn / Post Mawr^°	near Pen-cae · Ceredigion	—	stepped	3396 m	110 m	3.2%	13.0%	High
Llanbedr Dyffryn Clwyd to Gyrn^°	near Llanbedr-Dyffryn-Clwyd · Sir Ddinbych / Denbighshire	—	sustained	2370 m	149 m	6.3%	18.1%	High
Llanberis Pass	near Bryant's Gully · Gwynedd	Wikipedia¹, Another 100⁵	sustained	1716 m	86 m	5.0%	11.3%	High
Llancowrid to Goetre Hill^°	near Cwmberllan Dingle · Powys	—	stepped	2355 m	100 m	4.2%	≈26.4%	Good
Llandderfel to Carnedd Wen^°	near Llandderfel · Gwynedd	—	stepped	2906 m	221 m	7.6%	≈26.4%	Good
Llandecwyn to Bryn Bwbach^°	near Bryn Bwbach · Gwynedd	—	sustained	1271 m	86 m	6.8%	≈27.8%	Good
Llandeilo Road	near Glanaman · Sir Gaerfyrddin / Carmarthenshire	—	stepped	2628 m	129 m	4.9%	≈29.8%	Good
Llanellen to Cefn y Galchen^°	near Llanellen · Sir Fynwy / Monmouthshire	—	sustained	5964 m	452 m	7.6%	≈21.5%	Good
Llanellen to Coed y Prior^°	near Llanellen · Sir Fynwy / Monmouthshire	—	sustained	958 m	138 m	14.4%	≈26.7%	Good
Llanfach Road	near Llanfach · Caerffili / Caerphilly	—	sustained	1737 m	187 m	10.8%	≈20.9%	Good
Llanfihangel-y-Creuddyn to Pant-y-crug		—	stepped	1494 m	96 m	6.4%	25.4%	Good
Llangadog to Pentir-bach		—	stepped	2117 m	69 m	3.2%	≈26.4%	Good
Llangollen to Blaen-Bache Dingle^°	near Llangollen · Sir Ddinbych / Denbighshire	—	sustained	2680 m	279 m	10.4%	≈30.9%	Needs confirmation
Llanguicke Road	near Cwm Siôn · Castell-nedd Port Talbot / Neath Port Talbot	—	sustained	1172 m	156 m	13.3%	≈28.7%	Good
Llangynidr to Cwm Cleisfer^°	near Cwm Cleisfer · Powys	—	sustained	2044 m	149 m	7.3%	≈27.2%	Good
Llanilid to Ruthin^°	near Ruthin · Bro Morgannwg / the Vale of Glamorgan	—	stepped	1616 m	31 m	1.9%	≈12.0%	Needs confirmation
Llanybydder to Mynydd Llanybyther^°	near Ceunant Fâch · Sir Gaerfyrddin / Carmarthenshire	—	sustained	6003 m	286 m	4.8%	15.2%	Good
Llawr-y-glyn to Glyntrefnant^°	near Llawr-y-glyn · Powys	—	sustained	1033 m	131 m	12.6%	≈26.7%	Good
Llwynmawr to Bedwlwyn^°	near Pentre Cilgwyn · Wrecsam / Wrexham	—	sustained	1808 m	159 m	8.8%	26.1%	Needs confirmation
Lon Bribwll	near Llanbedrog · Gwynedd	—	stepped	635 m	40 m	6.3%	≈27.2%	Needs confirmation
Lower Harper's Road	near Victoria Village · Torfaen	—	stepped	1502 m	114 m	7.6%	≈26.1%	Good
Lower Stoney Road	near Victoria Village · Torfaen	—	stepped	623 m	62 m	10.0%	≈26.1%	Good
Lôn Nant Stigallt	near Llwyn-hudol · Gwynedd	—	sustained	917 m	60 m	6.5%	≈27.7%	Good
Maesyffynnon Terrace	near Tonypandy · Rhondda Cynon Taf	—	stepped	364 m	38 m	10.5%	21.8%	High
Melin-y-coed to Pant-y-maes^°	near Nant Bwlch-y-gwynt · Conwy	—	sustained	2452 m	262 m	10.7%	≈30.3%	Needs confirmation
Milltir Gerrig		Wikipedia¹	sustained	5940 m	325 m	5.5%	≈11.3%	Good
Minffordd to Cwm Rhwyddfor^°	near Ffynnon Cwm · Gwynedd	Wikipedia¹, Warren app⁴	sustained	2505 m	148 m	5.9%	12.0%	High
Moel Cwm yr Eglwys to Bwlch Oerddrws^°	near Cwm Cerist · Gwynedd	Wikipedia¹	sustained	2227 m	191 m	8.6%	16.5%	High
Mount Pleasant Terrace	near Miskin · Rhondda Cynon Taf	—	sustained	724 m	62 m	8.5%	21.6%	High
Mount Road	near Penrhiw · Caerffili / Caerphilly	—	stepped	825 m	95 m	11.5%	≈26.5%	Good
Mountain Road	near Port Talbot · Castell-nedd Port Talbot / Neath Port Talbot	—	stepped	514 m	53 m	10.4%	≈31.4%	Good
Mountain Road	near Ty-Sign · Caerffili / Caerphilly	—	sustained	3884 m	274 m	7.0%	≈26.5%	Needs confirmation
Nant-y-Rhiw to Moel Trefriw^°	near Nant-y-Rhiw · Conwy	—	sustained	4096 m	279 m	6.8%	≈25.6%	Good
New Mills to Ceunant y Garys^°	near New Mills · Powys	—	sustained	1951 m	201 m	10.3%	≈22.8%	Needs confirmation
Newgale Hill	near Newgale · Sir Benfro / Pembrokeshire	Warren app⁴	sustained	836 m	83 m	9.9%	21.7%	High
Onen to Pen-y-lan^°	near Onen · Sir Fynwy / Monmouthshire	—	sustained	1489 m	111 m	7.5%	≈27.8%	Good
Panorama Walk	near Cwrt · Gwynedd	—	stepped	1296 m	89 m	6.9%	26.4%	Good
Panorama Walk		—	sustained	2851 m	165 m	5.8%	≈28.7%	Good
Pant Du	near Vale of Llangollen · Sir Ddinbych / Denbighshire	—	sustained	825 m	101 m	12.3%	≈29.4%	Good
Pant Glâs to Bryn-y-gôg		—	stepped	1675 m	103 m	6.2%	20.3%	High
Parc Road	near Graig Trewyddfa · Abertawe / Swansea	—	sustained	413 m	43 m	10.3%	20.8%	High
Parc-Seymour to Castell-prin		—	stepped	478 m	48 m	10.1%	≈29.5%	Good
Parc-y-rhôs to Mynydd Pencarreg^°	near Parc-y-rhôs · Sir Gaerfyrddin / Carmarthenshire	—	sustained	5901 m	276 m	4.7%	≈19.0%	Needs confirmation
Park Road	near Rhondda Fach · Rhondda Cynon Taf	—	sustained	899 m	76 m	8.5%	25.8%	High
Park Street	near Cwm Clydach · Rhondda Cynon Taf	—	stepped	996 m	76 m	7.6%	23.0%	High
Partrishow Hill to Partrishow^°	near Partrishow · Powys	—	sustained	2447 m	154 m	6.3%	≈27.8%	Good
Pea Royd Lane	near Stocksbridge	Tour of Britain⁷, National HC³	sustained	442 m	68 m	15.3%	≈19.2%	Needs confirmation
Pen y Darren to Dinas^°	near Cwm Nant-y-glo · Sir Gaerfyrddin / Carmarthenshire	—	sustained	1800 m	64 m	3.5%	25.3%	High
Pen-y-Ffridd	near Rhiwlas · Gwynedd	—	sustained	1509 m	154 m	10.2%	17.0%	Good
Pen-y-lan to Llangattock Vibon Avel		—	stepped	677 m	60 m	8.8%	≈26.5%	Good
Pendine Hill	near Pendine · Sir Gaerfyrddin / Carmarthenshire	tag: 20% (2026)	sustained	863 m	88 m	10.2%	19.6%	High
Penglais Hill	near Buarth Mawr · Ceredigion	sign: 11% (2026, via OSM)	sustained	1310 m	97 m	7.4%	11.2%	High
Pentre-dwfr to Moel y Faen^°	near Pentre-dwfr · Sir Ddinbych / Denbighshire	—	sustained	1957 m	216 m	11.0%	21.1%	High
Penygraig Terrace	near Ynysybwl · Rhondda Cynon Taf	—	sustained	445 m	46 m	10.4%	20.3%	High
Penygraigwen to Llanwonno^°	near Cwm Hafod · Rhondda Cynon Taf	—	sustained	7613 m	265 m	3.5%	18.8%	Good
Ponthir Road	near Caerllion · Casnewydd / Newport	tag: 20% (2026)	sustained	242 m	17 m	7.0%	12.4%	High
Pontrobert to Llanfihangel-yng-Ngwynfa^°	near Cwm Einion · Powys	—	stepped	5432 m	172 m	3.2%	≈26.1%	Good
Pound Lane	near Llwynderw · Powys	—	sustained	1461 m	154 m	10.5%	≈29.2%	Good
Prenol to Pont Bronferiaeth^°	near The Dell · Conwy	—	stepped	2442 m	128 m	5.2%	≈26.7%	Good
Primrose Hill	near Pwllhobi · Ceredigion	tag: 12% (2026)	sustained	310 m	28 m	9.0%	14.7%	High
Rhigos Road	near Tynewydd · Rhondda Cynon Taf	100 Climbs²	sustained	6004 m	305 m	5.1%	8.6%	High
Rhiw Fain	near Cwm Perlla · Ceredigion	—	sustained	1176 m	132 m	11.2%	22.2%	Good
Rhiw Syr Dafydd	near Rock · Caerffili / Caerphilly	—	sustained	125 m	26 m	20.6%	≈29.6%	Good
Rhyd to Llandygwydd		—	stepped	1512 m	85 m	5.6%	≈29.1%	Good
Rhyd-y-foel to Coed Bettws		—	sustained	1266 m	134 m	10.6%	≈27.5%	Good
Rhyd-y-gwin to Tor Clawdd^°	near Cwm Clydach · Abertawe / Swansea	—	sustained	3579 m	196 m	5.5%	≈28.8%	Needs confirmation
Rhyd-y-saint to Bryn-têg^°	near Rhyd-y-saint · Sir Gaerfyrddin / Carmarthenshire	—	sustained	1531 m	52 m	3.4%	23.9%	High
Risca to Cwm Byr^°	near Risca · Caerffili / Caerphilly	—	sustained	1122 m	122 m	10.9%	≈29.0%	Good
Roman Reach	near St Julians · Casnewydd / Newport	tag: 20% (2026)	sustained	396 m	20 m	5.1%	10.1%	High
Roman Way	near Caerllion · Casnewydd / Newport	tag: 30% (2021)	sustained	566 m	22 m	3.8%	12.1%	High
Rosedale Chimney Bank	near Rosedale Abbey · North Yorkshire	100 Climbs², National HC³, Wikipedia¹	sustained	1107 m	149 m	13.4%	26.6%	High
Route Des Alpes		—	stepped	2169 m	148 m	6.8%	≈31.0%	Good
Ruthin Road	near Gwernymynydd · Sir y Fflint / Flintshire	—	sustained	2228 m	111 m	5.0%	11.3%	Good
Sarn Mellteyrn to Mynydd Rhiw^°	near Sarn Mellteyrn · Gwynedd	—	sustained	1793 m	151 m	8.4%	21.4%	Needs confirmation
School Street	near Maerdy · Rhondda Cynon Taf	—	sustained	497 m	53 m	10.7%	20.1%	High
Sennybridge to Yr Allt^°	near Cwm Clydach · Powys	—	sustained	1412 m	56 m	3.9%	≈29.5%	Good
Soar Road	near Talsarnau · Gwynedd	tag: 20% (2026)	sustained	396 m	48 m	12.0%	≈21.5%	Good
Springfield Road	near Maerdy · Rhondda Cynon Taf	—	sustained	410 m	29 m	7.2%	20.0%	High
Station Road	near Clydach · Sir Fynwy / Monmouthshire	—	sustained	1988 m	221 m	11.1%	≈26.4%	Good
Strada Florida Trailhead (Southernmost) to Pen y Cnwc^°	near Coed Nant-yr-hwch · Powys	—	stepped	2113 m	160 m	7.6%	22.3%	High
Sunny Bank	near Aberhonddu · Powys	—	sustained	451 m	39 m	8.6%	23.1%	High
Swansea Road		—	sustained	1815 m	80 m	4.4%	22.3%	High
Tal-y-bont to Pen-y-gaer^°	near Llanbedr-y-cennin · Conwy	—	sustained	3381 m	335 m	9.9%	23.6%	Needs confirmation
Tan Yr Allt Avenue	near Mochdre · Conwy	—	stepped	611 m	58 m	9.5%	23.0%	High
The Conduit	near Trefaldwyn · Powys	—	stepped	743 m	72 m	9.6%	27.5%	Needs confirmation
The Hendre to Pen-y-lan^°	near The Hendre · Sir Fynwy / Monmouthshire	—	sustained	2447 m	102 m	4.2%	≈26.5%	Needs confirmation
The Struggle (Kirkstone Road)	near Ambleside · Westmorland and Furness	100 Climbs², National HC³	sustained	1287 m	157 m	12.2%	23.2%	Good
Trallong to Cwm Brynych^°	near Cwm Camlais-fach · Powys	—	sustained	4833 m	160 m	3.3%	24.7%	Good
Tredegar Avenue	near Llanharan · Rhondda Cynon Taf	tag: 20% (2026)	sustained	228 m	21 m	9.4%	16.6%	High
Trefriw to Llanrhychwyn^°	near Llanrhychwyn · Conwy	—	sustained	2093 m	201 m	9.6%	≈26.9%	Good
Treharris Mountain Road	near Treharris · Merthyr Tudful / Merthyr Tydfil	—	sustained	3562 m	240 m	6.7%	22.0%	High
Trinity View	near Pilton Vale · Casnewydd / Newport	tag: 40% (2021)	sustained	602 m	80 m	13.3%	≈22.9%	Good
Troed-y-Rhiw Road		—	stepped	2603 m	224 m	8.6%	≈26.3%	Good
Twtil	near Harlech · Gwynedd	tag: 25% (2026)	sustained	352 m	50 m	14.1%	21.5%	Good
Twyn Gof Common to Cwm Dyfnant^°	near Cwm Dyfnant · Powys	—	sustained	2933 m	200 m	6.8%	≈26.4%	Good
Twyn-Garreg-Wen to Cwm Crew^°	near Cwm Crew · Powys	—	sustained	1953 m	78 m	4.0%	10.1%	High
Ty Canol Lane	near Machen · Caerffili / Caerphilly	—	sustained	2033 m	210 m	10.3%	18.9%	Good
Ty Gwyn Road	near Cwlach · Conwy	tag: 20% (2026)	sustained	841 m	96 m	11.4%	19.4%	High
Tylwch to Brynposteg Hill^°	near Cwm Jonathan · Powys	—	sustained	4281 m	103 m	2.4%	20.0%	High
Tylwch to Oldchapel Hill		—	sustained	1916 m	121 m	6.3%	23.8%	High
Unnamed lane near Llanfihangel-y-Creuddyn		—	stepped	1171 m	114 m	9.7%	≈27.1%	Good
Vine Row	near Ystalyfera · Castell-nedd Port Talbot / Neath Port Talbot	—	sustained	667 m	82 m	12.3%	≈28.5%	Good
Welsh Harp Hollow	near Cwm y Sul · Powys	—	sustained	3695 m	304 m	8.2%	23.1%	Good
Wenallt to Cwm Grognant^°	near Cwm Grognant · Ceredigion	—	sustained	1088 m	86 m	7.9%	≈20.1%	Good
Wern-llaeth to Graig Ddu^°	near Graig Ddu · Ceredigion	—	sustained	558 m	47 m	8.3%	11.5%	High
Windsor Road	near Six Bells · Blaenau Gwent	—	sustained	448 m	40 m	9.0%	20.4%	High
Wood Street	near Maerdy · Rhondda Cynon Taf	—	sustained	245 m	29 m	12.0%	20.0%	High
Woodland Park Road	near Beechwood · Casnewydd / Newport	—	sustained	808 m	60 m	7.4%	23.7%	High
Wrynose Pass	near Green Crag · Westmorland and Furness	100 Climbs², Wikipedia¹	sustained	1028 m	108 m	10.5%	24.6%	High
Yr Allt		—	sustained	537 m	57 m	10.5%	≈27.8%	Good
Yr Allt	near Allt · Sir Gaerfyrddin / Carmarthenshire	—	sustained	562 m	51 m	9.0%	≈27.8%	Good

° provisional name — auto-suggested from nearby map places, no local-usage evidence; renames welcome (each climb page has the details).

Sources: ¹ Wikipedia · ² 100 Greatest Cycling Climbs (Simon Warren) · ³ British National Hill Climb Championship · ⁴ Simon Warren 100 Climbs app (Wales collections) · ⁵ Another 100 Greatest Cycling Climbs (Simon Warren) · ⁶ Guinness World Records · ⁷ Tour of Britain