BETA — measurements and names under active refinement. Seen a sign, a gate, or a better name? Report it — no account needed (photos welcome via GitHub).

UK Climb Survey

Reproducible LiDAR gradient ladders for British road climbs. Every maximum states its measurement distance — because a hill can honestly be 32% over 2 m and 25% over 100 m at once. How to read these numbers →

Steepest 10 m

#	Climb	Max	Length	Overall
1	Berwyn to Geraint Hill^°	≈42.4%	3790 m	7.5%
2	Llangollen to Blaen-Bache Dingle^°	≈41.3%	2680 m	10.4%
3	Rhiw Syr Dafydd	≈40.0%	125 m	20.6%
4	Sennybridge to Yr Allt^°	39.7%	1412 m	3.9%
5	Mountain Road	≈39.7%	514 m	10.4%
6	Melin-y-coed to Pant-y-maes^°	≈38.2%	2452 m	10.7%
7	Yr Allt	≈37.4%	537 m	10.5%
8	Yr Allt	≈37.4%	562 m	9.0%
9	Allt y Badi (south side)	≈37.4%	2707 m	9.0%
10	Fforest Road	≈37.4%	925 m	12.5%
11	Bethlehem to Carn Powell^°	≈36.7%	3549 m	5.7%
12	Llandeilo Road	≈36.7%	2628 m	4.9%
13	Cwm Sŷch to Cwm Dyfnant	≈36.5%	2681 m	6.6%
14	Ffordd Pen Llech	≈36.3%	237 m	17.2%
15	Hafod Lane	≈36.0%	2898 m	4.5%

≈ measured under tree canopy or near a structure at this window — the value stands but is less certain (not necessarily wrong, not necessarily right). Each climb page details what was flagged and why.

Steepest 25 m

#	Climb	Max	Length	Overall
1	Ffordd Pen Llech	≈32.6%	237 m	17.2%
2	Allt y Badi (south side)	≈31.7%	2707 m	9.0%
3	Mountain Road	≈31.4%	514 m	10.4%
4	Route Des Alpes	≈31.0%	2169 m	6.8%
5	Llangollen to Blaen-Bache Dingle^°	≈30.9%	2680 m	10.4%
6	Melin-y-coed to Pant-y-maes^°	≈30.3%	2452 m	10.7%
7	Lane near Cellan^°	≈30.1%	2094 m	5.9%
8	Heol Feurig	≈30.0%	284 m	11.5%
9	Llandeilo Road	≈29.8%	2628 m	4.9%
10	Bethlehem to Carn Powell^°	≈29.6%	3549 m	5.7%
11	Coronation Street	29.6%	307 m	11.4%
12	Rhiw Syr Dafydd	≈29.6%	125 m	20.6%
13	Sennybridge to Yr Allt^°	≈29.5%	1412 m	3.9%
14	Parc-Seymour to Castell-prin	≈29.5%	478 m	10.1%
15	Lane near Blaenllechau^°	≈29.4%	447 m	6.7%

Steepest 50 m

#	Climb	Max	Length	Overall
1	Ffordd Pen Llech	≈29.8%	237 m	17.2%
2	Melin-y-coed to Pant-y-maes^°	≈29.5%	2452 m	10.7%
3	Mountain Road	≈28.5%	514 m	10.4%
4	Llanguicke Road	≈28.4%	1172 m	13.3%
5	Ffordd Bryn Fran	≈27.9%	2943 m	9.9%
6	Dinas Oleu Lane	≈27.8%	198 m	21.5%
7	Ffordd Llwyn Du	27.4%	1494 m	12.2%
8	Pound Lane	≈27.0%	1461 m	10.5%
9	Lane near Fron^°	≈27.0%	492 m	18.1%
10	Cefn Llan	≈26.6%	218 m	19.4%
11	Heol Feurig	≈26.5%	284 m	11.5%
12	Bryncethin Road	≈26.5%	1635 m	8.9%
13	Cwrdy Lane	≈26.4%	1757 m	9.0%
14	Coronation Street	26.3%	307 m	11.4%
15	Clifton Hill	26.2%	141 m	23.9%

Steepest 100 m

#	Climb	Max	Length	Overall
1	Ffordd Pen Llech	≈26.5%	237 m	17.2%
2	Dinas Oleu Lane	≈25.3%	198 m	21.5%
3	Cefn Llan	≈25.1%	218 m	19.4%
4	Clifton Hill	24.9%	141 m	23.9%
5	Mount Road	≈24.4%	825 m	11.5%
6	Ffordd Bryn Fran	≈24.4%	2943 m	9.9%
7	Pant Du	≈24.3%	825 m	12.3%
8	Vine Row	≈24.1%	667 m	12.3%
9	Melin-y-coed to Pant-y-maes^°	≈24.0%	2452 m	10.7%
10	Ffordd Llwyn Du	24.0%	1494 m	12.2%
11	Partrishow Hill to Partrishow^°	≈23.9%	2447 m	6.3%
12	Pound Lane	≈23.9%	1461 m	10.5%
13	Cwrdy Lane	≈23.8%	1757 m	9.0%
14	Allt y Badi (south side)	≈23.6%	2707 m	9.0%
15	Lane near Glyn Ceiriog^°	≈23.5%	522 m	11.4%

Largest elevation gain

#	Climb	Net rise	Total ascent	Length	Overall
1	Cwm y Gâth to Bryn-y-Fedwen	456 m	500 m	8271 m	5.5%
2	Llanellen to Cefn y Galchen^°	452 m	482 m	5964 m	7.6%
3	Adams Street to Cerrig yr Hafan	380 m	432 m	8383 m	4.5%
4	Blaenavon Road	367 m	371 m	4320 m	8.5%
5	Tal-y-bont to Pen-y-gaer^°	335 m	346 m	3381 m	9.9%
6	Lawnt to Tir Mostyn^°	331 m	430 m	9367 m	3.5%
7	Dardy to Blaen Onneu^°	328 m	361 m	6272 m	5.2%
8	Llangynog to Cwm Pydew	325 m	337 m	5940 m	5.5%
9	Cyffredyn to Blaen Onneu^°	323 m	339 m	4794 m	6.7%
10	Hardknott Pass	315 m	318 m	3119 m	10.1%
11	Erwyd to Llangynog	308 m	345 m	5937 m	5.2%
12	Rhigos Road	305 m	308 m	6004 m	5.1%
13	Welsh Harp Hollow	304 m	315 m	3695 m	8.2%
14	Ffordd-las to Hay Bluff^°	294 m	382 m	6927 m	4.2%
15	Ffordd Bryn Fran	292 m	312 m	2943 m	9.9%

Net rise is the endpoint elevation difference (what overall gradient is computed from); total ascent counts every metre climbed, including dips regained.

All climbs (255)

Climb	Area	Known from	Shape	Length	Net rise	Overall	Max 25 m
Aberarth to Graig Ddu		—	sustained	1967 m	98 m	5.0%	12.9%
Aberdyfi to Ffridd Cefn-isaf^°	near Aberdyfi · Gwynedd	—	sustained	1610 m	181 m	11.2%	20.9%
Aberedw to Pontsioni^°	near Aberedw · Powys	—	sustained	654 m	93 m	14.3%	26.5%
Aberffrwd Hill	near Aberffrwd · Ceredigion	—	sustained	2372 m	237 m	10.0%	≈26.1%
Adams Street to Cerrig yr Hafan		—	sustained	8383 m	380 m	4.5%	14.5%
Allt Bron Philip	near Llanddona · Sir Ynys Mon / Isle of Anglesey	—	sustained	1442 m	139 m	9.6%	≈26.2%
Allt Goch Fawr	near Nant Meigan · Sir Ynys Mon / Isle of Anglesey	tag: 25% (2026)	stepped	1266 m	83 m	6.5%	≈15.0%
Allt y Badi (south side)	near Glyn Ceiriog · Wrecsam / Wrexham	tag: 25% (2026)	stepped	2707 m	243 m	9.0%	≈31.7%
Aston Expressway	near Ewloe · Sir y Fflint / Flintshire	—	sustained	747 m	32 m	4.3%	11.7%
Bank Road	near Matlock · Derbyshire	100 Climbs¹	sustained	530 m	57 m	10.7%	15.5%
Bedwellty Road	near Aberbargoed · Caerffili / Caerphilly	—	sustained	1891 m	144 m	7.6%	21.0%
Berwyn to Blaen-Bache Dingle^°	near The Dingle · Sir Ddinbych / Denbighshire	—	sustained	6052 m	276 m	4.6%	≈21.7%
Berwyn to Geraint Hill^°	near The Dingle · Sir Ddinbych / Denbighshire	—	sustained	3790 m	286 m	7.5%	≈20.9%
Bethlehem to Carn Powell^°	near Capel Dingle · Sir Gaerfyrddin / Carmarthenshire	—	sustained	3549 m	201 m	5.7%	≈29.6%
Bettws Gwerfil Goch to Pen Hafoty-Foel^°	near Bettws Gwerfil Goch · Sir Ddinbych / Denbighshire	—	sustained	1608 m	97 m	6.0%	≈27.2%
Bevan Avenue	near Mochdre · Conwy	—	stepped	660 m	61 m	9.2%	23.0%
Blackvein Mountain Road	near Glenside · Caerffili / Caerphilly	—	sustained	1688 m	176 m	10.4%	≈25.9%
Blaenavon Road		—	sustained	4320 m	367 m	8.5%	≈14.5%
Boughrood to Trewern Hill^°	near Llanstephan · Powys	—	sustained	4401 m	228 m	5.2%	21.9%
Brace Avenue	near Blaenau Gwent · Blaenau Gwent	—	sustained	937 m	60 m	6.4%	21.1%
Brongwyn to Capel Tygwydd^°	near Troed-y-rhiw-Siôn · Ceredigion	—	stepped	1288 m	64 m	5.0%	≈26.0%
Bryn Dolwen to Tyddyn^°	near Cwm y Glog · Powys	—	sustained	1499 m	85 m	5.7%	20.2%
Bryn Rhyd-yr-Arian to Mynydd Tryfan^°	near Dyffryn Aled · Conwy	—	sustained	2925 m	148 m	5.1%	≈29.0%
Bryn Road	near Pen-Rhiw-fawr · Castell-nedd Port Talbot / Neath Port Talbot	—	sustained	395 m	49 m	12.4%	21.8%
Bryncethin Road	near Cwm Garnant · Castell-nedd Port Talbot / Neath Port Talbot	—	sustained	1635 m	146 m	8.9%	≈28.2%
Brynllys to Bwlch Oerddrws^°	near Cwm Cerist · Gwynedd	—	stepped	5159 m	248 m	4.8%	16.5%
Bush Road	near Miskin · Rhondda Cynon Taf	—	sustained	466 m	60 m	12.8%	22.0%
Bwlch Esgair Gelli		—	sustained	2505 m	164 m	6.5%	23.7%
Bwlch Penbarras	near Llanbedr-Dyffryn-Clwyd · Sir Ddinbych / Denbighshire	100 Climbs¹	sustained	2324 m	260 m	11.2%	≈24.4%
Bwlch-y-Clawdd Road	near Cwm Dâr · Rhondda Cynon Taf	100 Climbs¹	sustained	4804 m	270 m	5.6%	8.9%
Cairo Street	near Dinas · Rhondda Cynon Taf	—	sustained	358 m	34 m	9.5%	22.3%
Capel Bangor to Pant-y-crug	near Pant-y-crûg · Ceredigion	—	sustained	1389 m	145 m	10.5%	≈21.0%
Cefn Llan	near Cwmpadarn · Ceredigion	sign: 32% (2025, via OSM)	sustained	218 m	42 m	19.4%	≈27.4%
Cefn Vron Hill to Bryn^°	near Anchor · Shropshire	—	sustained	649 m	50 m	7.7%	20.7%
Ceunant Gorddinan to Ffridd-y-Bwlch		—	sustained	2266 m	130 m	5.7%	11.6%
Charles Street	near Trealaw · Rhondda Cynon Taf	—	sustained	915 m	97 m	10.6%	20.7%
Clifton Hill	near Abertawe · Abertawe / Swansea	—	sustained	141 m	34 m	23.9%	27.8%
Clynnog Fawr to Bwlch Mawr^°	near Capel Uchaf · Gwynedd	—	stepped	3170 m	192 m	6.1%	22.8%
Commin Road	near Aberbargoed · Caerffili / Caerphilly	—	stepped	1344 m	119 m	8.9%	21.0%
Commins Coch to Darowen^°	near Darowen · Powys	—	sustained	2468 m	119 m	4.8%	26.5%
Constitution Hill	near Mount Pleasant · Abertawe / Swansea	Wikipedia²	sustained	348 m	61 m	17.4%	21.9%
Coronation Street	near Wyndham · Pen-y-bont ar Ogwr / Bridgend	—	stepped	307 m	35 m	11.4%	29.6%
Craig Y Pant to Foel Y Groes^°	near Cwm Cerddin · Gwynedd	—	sustained	1214 m	188 m	15.5%	23.8%
Creigiau'r Llyn to Foel Y Groes^°	near Cwm Eunant · Powys	—	sustained	6349 m	286 m	4.5%	≈19.7%
Crimea Pass (Bwlch y Gorddinan)	near Tal-y-waenydd · Gwynedd	—	sustained	2705 m	260 m	9.6%	≈18.4%
Crossway to Tyn Green Castle^°	near Crossway · Powys	—	stepped	2848 m	112 m	3.9%	22.1%
Cwm Dulais to Cwm Ysgiach^°	near Cwm Dulais · Abertawe / Swansea	—	stepped	1908 m	39 m	2.0%	27.1%
Cwm Ffrydlan to Bryn Mawr^°	near Cwm Esgaireira · Powys	—	stepped	3364 m	193 m	5.8%	≈27.0%
Cwm Llwynau to Cwm Cnyw^°	near Cwm Llwynau · Torfaen	—	stepped	1135 m	70 m	6.2%	≈26.8%
Cwm Sŷch to Cwm Dyfnant		—	sustained	2681 m	177 m	6.6%	≈26.4%
Cwm Wern-ddu to Llanfihangel-y-Creuddyn^°	near Llanfihangel-y-Creuddyn · Ceredigion	—	sustained	1549 m	98 m	6.3%	≈20.1%
Cwm y Gâth to Bryn-y-Fedwen		—	sustained	8271 m	456 m	5.5%	22.6%
Cwm-hirblyg to Glyn Llydan^°	near Glyn Llydan · Sir Gaerfyrddin / Carmarthenshire	—	sustained	2890 m	96 m	3.3%	≈26.7%
Cwm-hirblyg to Pen Rhiw-Wen^°	near Cwm Nant-dywyll · Sir Gaerfyrddin / Carmarthenshire	—	sustained	5282 m	272 m	5.2%	18.7%
Cwrdy Lane	near Penyrheol · Torfaen	—	stepped	1757 m	158 m	9.0%	≈28.7%
Cyffredyn to Blaen Onneu^°	near Cwm Cleisfer · Powys	—	sustained	4794 m	323 m	6.7%	16.2%
Dardy to Blaen Onneu^°	near Cwm Onnau · Powys	—	sustained	6272 m	328 m	5.2%	≈23.2%
Derwen Lane	near Penrhyn-side · Conwy	—	stepped	1188 m	78 m	6.5%	27.2%
Devil's Staircase	near Coed Nant-yr-hwch · Powys	Another 100³	sustained	841 m	111 m	13.2%	24.5%
Devil's Staircase (west side)	near Coed Nant-yr-hwch · Powys	tag: 25% (2026)	stepped	2348 m	181 m	7.7%	22.3%
Dinas Oleu Lane	near Abermaw · Gwynedd	—	sustained	198 m	43 m	21.5%	≈29.4%
Discoed to Upper Dunn's Plantation^°	near Thorn · Powys	—	stepped	2144 m	164 m	7.7%	≈26.2%
Dolhendre to Carndochan^°	near Rhosdylluan · Gwynedd	—	sustained	642 m	53 m	8.3%	≈26.5%
Duffield's Lane	near Upper Redbrook · Sir Fynwy / Monmouthshire	—	sustained	993 m	102 m	10.3%	≈26.0%
Dyffryn Conwy to Mynydd Cauedig		—	sustained	1784 m	176 m	9.9%	≈26.8%
Eisingrug to Moel y Geifr^°	near Eisingrug · Gwynedd	—	sustained	2149 m	217 m	10.1%	≈22.0%
Erwyd to Llangynog		—	sustained	5937 m	308 m	5.2%	≈18.9%
Felindre to Cwm Hyfryd^°	near Cwmpengraig · Sir Gaerfyrddin / Carmarthenshire	—	sustained	5214 m	262 m	5.0%	≈17.6%
Ffordd Bryn Fran	near Pentre'r Felin · Conwy	—	sustained	2943 m	292 m	9.9%	≈28.1%
Ffordd Llwyn Du	near Pentre'r Felin · Conwy	—	sustained	1494 m	182 m	12.2%	28.3%
Ffordd Pen Llech	near Harlech · Gwynedd	Guinness⁴	sustained	237 m	41 m	17.2%	≈32.6%
Ffordd Rhiwlas		—	stepped	2601 m	159 m	6.1%	≈26.5%
Ffordd y Graig	near Trebannws · Castell-nedd Port Talbot / Neath Port Talbot	—	sustained	1632 m	173 m	10.6%	≈26.2%
Ffordd-las to Hay Bluff^°	near Tregoyd · Powys	—	sustained	6927 m	294 m	4.2%	≈28.7%
Fforest Road	near Caegarw · Rhondda Cynon Taf	—	sustained	925 m	115 m	12.5%	≈26.8%
Garth to Cwmsymlog^°	near Pen-rhiw-newydd · Ceredigion	—	sustained	4880 m	273 m	5.6%	18.5%
Georges Delight	near Gaer-fawr · Sir Fynwy / Monmouthshire	—	stepped	2215 m	162 m	7.3%	≈26.4%
Gladestry to Hengoed		—	stepped	1821 m	100 m	5.5%	≈26.5%
Glamorgan Street	near Penrhiwceiber · Rhondda Cynon Taf	—	sustained	1148 m	113 m	9.8%	21.7%
Glyndyfrdwy to Moel Morfydd^°	near Glyndyfrdwy · Sir Ddinbych / Denbighshire	—	stepped	3629 m	279 m	7.7%	25.5%
Govilon to Gilwern Hill^°	near Cwm Llanwenarth · Sir Fynwy / Monmouthshire	—	sustained	1788 m	187 m	10.5%	≈22.2%
Greenfield Place	near Middle Coedcae · Torfaen	—	sustained	600 m	48 m	7.9%	22.3%
Groeslon-waun to Cefn Du^°	near Groeslon · Gwynedd	—	stepped	1714 m	98 m	5.7%	26.2%
Gully to Pen y Ffynnon^°	near Gully · Powys	—	stepped	1677 m	125 m	7.5%	27.5%
Gwyddelwern to Betws Gwerful Goch		—	sustained	3132 m	164 m	5.3%	≈26.2%
Hafod Lane	near Trehafod · Rhondda Cynon Taf	—	sustained	2898 m	130 m	4.5%	≈27.3%
Hafod-fan Road	near Six Bells · Blaenau Gwent	—	sustained	181 m	31 m	17.0%	20.4%
Halswell Street	near Tyntetown · Rhondda Cynon Taf	—	sustained	163 m	21 m	12.7%	20.7%
Hardknott Pass		100 Climbs¹	sustained	3119 m	315 m	10.1%	25.9%
Heartsease to Stanage Park^°	near Heartsease · Powys	—	sustained	894 m	70 m	7.9%	20.2%
Hen Ffordd	near Bwlch · Powys	—	sustained	419 m	40 m	9.4%	≈21.0%
Hendre Owen Road	near Duffryn · Castell-nedd Port Talbot / Neath Port Talbot	—	sustained	309 m	46 m	15.0%	23.1%
Henllys to Nant Carn^°	near Henllys · Torfaen	—	sustained	1553 m	187 m	12.1%	≈25.4%
Heol Calch	near Cwm Gored · Powys	—	stepped	925 m	86 m	9.3%	≈26.0%
Heol Feurig	near Dolgellau · Gwynedd	—	stepped	284 m	33 m	11.5%	≈30.0%
Heol Lan		—	stepped	2788 m	142 m	5.1%	≈26.3%
Heol y Banc	near Llygadywawr · Sir Gaerfyrddin / Carmarthenshire	—	sustained	1670 m	164 m	9.8%	21.9%
High Meadow to Hafodyrynys^°	near Cwm Hafod-fach · Caerffili / Caerphilly	—	stepped	4325 m	266 m	6.1%	≈24.0%
Hill Road	near Pontlottyn · Caerffili / Caerphilly	—	stepped	1187 m	114 m	9.6%	21.6%
Hill Street	near Cwm Ysgwydd-gwyn · Caerffili / Caerphilly	—	sustained	1697 m	146 m	8.6%	27.9%
Hill Terrace	near Carreg yr Eos · Sir Benfro / Pembrokeshire	—	sustained	589 m	58 m	9.8%	15.0%
Hillside		—	sustained	801 m	132 m	16.5%	24.6%
Horseshoe Pass		Nat HC 1971⁵	sustained	4543 m	276 m	6.1%	≈14.4%
Lane near Abercych^°	near Abercych · Sir Benfro / Pembrokeshire	—	stepped	684 m	73 m	10.6%	≈26.3%
Lane near Betws-y-coed	near Betws-y-Coed · Conwy	tag: 20% (2026)	sustained	1263 m	162 m	12.8%	≈21.6%
Lane near Blaen-y-Glyn	near Bannau Brycheiniog · Powys	tag: 20% (2026)	sustained	1515 m	180 m	11.8%	≈19.7%
Lane near Blaenllechau^°	near Blaenllechau · Rhondda Cynon Taf	—	stepped	447 m	30 m	6.7%	≈29.4%
Lane near Cellan^°	near Cellan · Ceredigion	—	stepped	2094 m	124 m	5.9%	≈30.1%
Lane near Ceunant		—	sustained	991 m	86 m	8.7%	≈26.4%
Lane near Cwrt	near Cwm Ffernol · Gwynedd	tag: 20% (2026)	sustained	1015 m	94 m	9.2%	24.4%
Lane near Dolgellau^°	near Dolgellau · Gwynedd	—	sustained	234 m	35 m	15.1%	20.3%
Lane near Fron^°	near Fron · Powys	—	sustained	492 m	89 m	18.1%	≈29.3%
Lane near Garndolbenmaen^°	near Garndolbenmaen · Gwynedd	—	stepped	722 m	65 m	9.0%	20.6%
Lane near Gilfach^°	near Gilfach · Caerffili / Caerphilly	—	stepped	352 m	28 m	7.8%	20.7%
Lane near Glascoed^°	near Glascoed · Powys	—	stepped	1360 m	101 m	7.5%	25.2%
Lane near Glyn Ceiriog^°	near Glyn Ceiriog · Wrecsam / Wrexham	—	stepped	522 m	60 m	11.4%	≈27.2%
Lane near Glyn Ceiriog^°	near Glyn Ceiriog · Wrecsam / Wrexham	—	sustained	1051 m	87 m	8.3%	≈27.2%
Lane near Glyn Saer^°	near Cwm-bychan · Sir Gaerfyrddin / Carmarthenshire	—	stepped	7043 m	150 m	2.1%	11.7%
Lane near Kilgwrrwg Common^°	near Kilgwrrwg · Sir Fynwy / Monmouthshire	—	stepped	1472 m	117 m	7.9%	≈27.5%
Lane near Leighton	near Pentre · Powys	tag: 20% (2026)	sustained	646 m	70 m	10.9%	≈22.8%
Lane near Llanarmon Mynydd Mawr	near Llanrhaeadr-ym-Mochnant · Powys	tag: 20% (2026)	sustained	762 m	85 m	11.1%	≈26.8%
Lane near Llanddeusant^°	near Llanddeusant · Sir Gaerfyrddin / Carmarthenshire	—	sustained	499 m	66 m	13.2%	≈27.4%
Lane near Llanedi^°	near Llanedi · Sir Gaerfyrddin / Carmarthenshire	—	stepped	1275 m	66 m	5.2%	20.3%
Lane near Llanfair Talhaearn^°	near Llanfair Talhaiarn · Conwy	—	sustained	1627 m	141 m	8.6%	20.4%
Lane near Llangadfan^°	near Llangadfan · Powys	—	sustained	546 m	56 m	10.2%	≈27.3%
Lane near Llanglydwen^°	near Llanglydwen · Sir Gaerfyrddin / Carmarthenshire	—	sustained	1839 m	96 m	5.2%	20.3%
Lane near Llanybri^°	near Llanybri · Sir Gaerfyrddin / Carmarthenshire	—	sustained	879 m	93 m	10.5%	≈26.4%
Lane near Llanystumdwy^°	near Llanystumdwy · Gwynedd	—	stepped	556 m	36 m	6.4%	≈27.0%
Lane near Maen-Offeren^°	near Maen-Offeren · Gwynedd	—	sustained	225 m	29 m	13.1%	25.3%
Lane near Maenan^°	near Maenan · Conwy	—	sustained	1027 m	138 m	13.5%	≈27.5%
Lane near Miskin^°	near Miskin · Rhondda Cynon Taf	—	stepped	752 m	70 m	9.3%	22.0%
Lane near Miskin^°	near Miskin · Rhondda Cynon Taf	—	sustained	315 m	47 m	14.9%	21.0%
Lane near Pont-Tyweli^°	near Pont-Tyweli · Sir Gaerfyrddin / Carmarthenshire	—	sustained	1898 m	104 m	5.5%	≈23.9%
Lane near Price Town^°	near Price Town · Pen-y-bont ar Ogwr / Bridgend	—	sustained	432 m	46 m	10.6%	22.9%
Lane near Rhyd-Meirionnydd		tag: 25%	sustained	4090 m	116 m	2.8%	13.9%
Lane near Stanleytown^°	near Stanleytown · Rhondda Cynon Taf	—	sustained	164 m	27 m	16.1%	28.4%
Lane near Stepaside^°	near Stepaside · Powys	—	sustained	1727 m	112 m	6.5%	≈26.3%
Lane near Ton Pentre^°	near Ton Pentre · Rhondda Cynon Taf	—	sustained	314 m	40 m	12.6%	≈28.5%
Lane near Trealaw^°	near Trealaw · Rhondda Cynon Taf	—	stepped	253 m	25 m	9.9%	≈24.5%
Lane near Ty'n-y-groes^°	near Ty'n-y-groes · Conwy	—	stepped	957 m	48 m	5.0%	≈26.2%
Lane near Wernffrwd^°	near Wernffrwd · Abertawe / Swansea	—	sustained	1264 m	81 m	6.4%	22.0%
Lane near Whitesands Bay^°	near Whitesands Bay · Sir Benfro / Pembrokeshire	—	sustained	610 m	48 m	7.9%	22.1%
Lane near Ystradfellte^°	near Ystradfellte · Powys	—	stepped	2317 m	79 m	3.4%	21.0%
Lawnt to Tir Mostyn^°	near Soar · Sir Ddinbych / Denbighshire	—	sustained	9367 m	331 m	3.5%	17.9%
Lewis Street	near Prospect Place · Torfaen	—	stepped	1483 m	87 m	5.9%	23.2%
Llanarth to Synod Inn / Post Mawr^°	near Pen-cae · Ceredigion	—	stepped	3396 m	110 m	3.2%	13.0%
Llanbedr Dyffryn Clwyd to Gyrn^°	near Llanbedr-Dyffryn-Clwyd · Sir Ddinbych / Denbighshire	—	sustained	2370 m	149 m	6.3%	18.1%
Llancowrid to Goetre Hill^°	near Cwmberllan Dingle · Powys	—	stepped	2355 m	100 m	4.2%	≈26.4%
Llandderfel to Carnedd Wen^°	near Llandderfel · Gwynedd	—	stepped	2906 m	221 m	7.6%	≈26.4%
Llandecwyn to Bryn Bwbach^°	near Bryn Bwbach · Gwynedd	—	sustained	1271 m	86 m	6.8%	≈27.8%
Llandeilo Road	near Glanaman · Sir Gaerfyrddin / Carmarthenshire	—	stepped	2628 m	129 m	4.9%	≈29.8%
Llanellen to Cefn y Galchen^°	near Llanellen · Sir Fynwy / Monmouthshire	—	sustained	5964 m	452 m	7.6%	≈21.5%
Llanellen to Coed y Prior^°	near Llanellen · Sir Fynwy / Monmouthshire	—	sustained	958 m	138 m	14.4%	≈26.7%
Llanfach Road	near Llanfach · Caerffili / Caerphilly	—	sustained	1737 m	187 m	10.8%	≈20.9%
Llanfihangel-y-Creuddyn to Pant-y-crug		—	stepped	1494 m	96 m	6.4%	25.4%
Llangadog to Pentir-bach		—	stepped	2117 m	69 m	3.2%	≈26.4%
Llangollen to Blaen-Bache Dingle^°	near Llangollen · Sir Ddinbych / Denbighshire	—	sustained	2680 m	279 m	10.4%	≈30.9%
Llanguicke Road	near Cwm Siôn · Castell-nedd Port Talbot / Neath Port Talbot	—	sustained	1172 m	156 m	13.3%	≈28.7%
Llangynidr to Cwm Cleisfer^°	near Cwm Cleisfer · Powys	—	sustained	2044 m	149 m	7.3%	≈27.2%
Llangynog to Cwm Pydew		—	sustained	5940 m	325 m	5.5%	≈11.3%
Llanilid to Ruthin^°	near Ruthin · Bro Morgannwg / the Vale of Glamorgan	—	stepped	1616 m	31 m	1.9%	≈12.0%
Llanybydder to Mynydd Llanybyther^°	near Ceunant Fâch · Sir Gaerfyrddin / Carmarthenshire	—	sustained	6003 m	286 m	4.8%	15.2%
Llawr-y-glyn to Glyntrefnant^°	near Llawr-y-glyn · Powys	—	sustained	1033 m	131 m	12.6%	≈26.7%
Llwynmawr to Bedwlwyn^°	near Pentre Cilgwyn · Wrecsam / Wrexham	—	sustained	1808 m	159 m	8.8%	26.1%
Lon Bribwll	near Llanbedrog · Gwynedd	—	stepped	635 m	40 m	6.3%	≈27.2%
Lower Harper's Road	near Victoria Village · Torfaen	—	stepped	1502 m	114 m	7.6%	≈26.1%
Lower Stoney Road	near Victoria Village · Torfaen	—	stepped	623 m	62 m	10.0%	≈26.1%
Lôn Nant Stigallt	near Llwyn-hudol · Gwynedd	—	sustained	917 m	60 m	6.5%	≈27.7%
Maesyffynnon Terrace	near Tonypandy · Rhondda Cynon Taf	—	stepped	364 m	38 m	10.5%	21.8%
Melin-y-coed to Pant-y-maes^°	near Nant Bwlch-y-gwynt · Conwy	—	sustained	2452 m	262 m	10.7%	≈30.3%
Minffordd to Cwm Rhwyddfor^°	near Ffynnon Cwm · Gwynedd	—	sustained	2505 m	148 m	5.9%	12.0%
Moel Cwm yr Eglwys to Bwlch Oerddrws^°	near Cwm Cerist · Gwynedd	—	sustained	2227 m	191 m	8.6%	16.5%
Mount Pleasant Terrace	near Miskin · Rhondda Cynon Taf	—	sustained	724 m	62 m	8.5%	21.6%
Mount Road	near Penrhiw · Caerffili / Caerphilly	—	stepped	825 m	95 m	11.5%	≈26.5%
Mountain Road	near Port Talbot · Castell-nedd Port Talbot / Neath Port Talbot	—	stepped	514 m	53 m	10.4%	≈31.4%
Mountain Road	near Ty-Sign · Caerffili / Caerphilly	—	sustained	3884 m	274 m	7.0%	≈26.5%
Nant-y-Rhiw to Moel Trefriw^°	near Nant-y-Rhiw · Conwy	—	sustained	4096 m	279 m	6.8%	≈25.6%
New Mills to Ceunant y Garys^°	near New Mills · Powys	—	sustained	1951 m	201 m	10.3%	≈22.8%
Newgale Hill	near Newgale · Sir Benfro / Pembrokeshire	—	sustained	836 m	83 m	9.9%	21.7%
Onen to Pen-y-lan^°	near Onen · Sir Fynwy / Monmouthshire	—	sustained	1489 m	111 m	7.5%	≈27.8%
Panorama Walk	near Cwrt · Gwynedd	—	stepped	1296 m	89 m	6.9%	26.4%
Panorama Walk		—	sustained	2851 m	165 m	5.8%	≈28.7%
Pant Du	near Vale of Llangollen · Sir Ddinbych / Denbighshire	—	sustained	825 m	101 m	12.3%	≈29.4%
Pant Glâs to Bryn-y-gôg		—	stepped	1675 m	103 m	6.2%	20.3%
Parc Road	near Graig Trewyddfa · Abertawe / Swansea	—	sustained	413 m	43 m	10.3%	20.8%
Parc-Seymour to Castell-prin		—	stepped	478 m	48 m	10.1%	≈29.5%
Parc-y-rhôs to Mynydd Pencarreg^°	near Parc-y-rhôs · Sir Gaerfyrddin / Carmarthenshire	—	sustained	5901 m	276 m	4.7%	≈19.0%
Park Road	near Rhondda Fach · Rhondda Cynon Taf	—	sustained	899 m	76 m	8.5%	25.8%
Park Street	near Cwm Clydach · Rhondda Cynon Taf	—	stepped	996 m	76 m	7.6%	23.0%
Partrishow Hill to Partrishow^°	near Partrishow · Powys	—	sustained	2447 m	154 m	6.3%	≈27.8%
Pea Royd Lane	near Stocksbridge	Tour of Britain⁶	sustained	442 m	68 m	15.3%	≈19.2%
Pen y Darren to Dinas^°	near Cwm Nant-y-glo · Sir Gaerfyrddin / Carmarthenshire	—	sustained	1800 m	64 m	3.5%	25.3%
Pen-y-Ffridd	near Rhiwlas · Gwynedd	—	sustained	1509 m	154 m	10.2%	17.0%
Pen-y-lan to Llangattock Vibon Avel		—	stepped	677 m	60 m	8.8%	≈26.5%
Pendine Hill	near Pendine · Sir Gaerfyrddin / Carmarthenshire	tag: 20% (2026)	sustained	863 m	88 m	10.2%	19.6%
Penglais Hill	near Buarth Mawr · Ceredigion	sign: 11% (2026, via OSM)	sustained	1310 m	97 m	7.4%	11.2%
Pentre-dwfr to Moel y Faen^°	near Pentre-dwfr · Sir Ddinbych / Denbighshire	—	sustained	1957 m	216 m	11.0%	21.1%
Penygraig Terrace	near Ynysybwl · Rhondda Cynon Taf	—	sustained	445 m	46 m	10.4%	20.3%
Penygraigwen to Llanwonno^°	near Cwm Hafod · Rhondda Cynon Taf	—	sustained	7613 m	265 m	3.5%	18.8%
Ponthir Road	near Caerllion · Casnewydd / Newport	tag: 20% (2026)	sustained	242 m	17 m	7.0%	12.4%
Pontrobert to Llanfihangel-yng-Ngwynfa^°	near Cwm Einion · Powys	—	stepped	5432 m	172 m	3.2%	≈26.1%
Pound Lane	near Llwynderw · Powys	—	sustained	1461 m	154 m	10.5%	≈29.2%
Prenol to Pont Bronferiaeth^°	near The Dell · Conwy	—	stepped	2442 m	128 m	5.2%	≈26.7%
Primrose Hill	near Pwllhobi · Ceredigion	tag: 12% (2026)	sustained	310 m	28 m	9.0%	14.7%
Rhigos Road	near Tynewydd · Rhondda Cynon Taf	100 Climbs¹	sustained	6004 m	305 m	5.1%	8.6%
Rhiw Fain	near Cwm Perlla · Ceredigion	—	sustained	1176 m	132 m	11.2%	22.2%
Rhiw Syr Dafydd	near Rock · Caerffili / Caerphilly	—	sustained	125 m	26 m	20.6%	≈29.6%
Rhyd to Llandygwydd		—	stepped	1512 m	85 m	5.6%	≈29.1%
Rhyd-y-foel to Coed Bettws		—	sustained	1266 m	134 m	10.6%	≈27.5%
Rhyd-y-gwin to Tor Clawdd^°	near Cwm Clydach · Abertawe / Swansea	—	sustained	3579 m	196 m	5.5%	≈28.8%
Rhyd-y-saint to Bryn-têg^°	near Rhyd-y-saint · Sir Gaerfyrddin / Carmarthenshire	—	sustained	1531 m	52 m	3.4%	23.9%
Risca to Cwm Byr^°	near Risca · Caerffili / Caerphilly	—	sustained	1122 m	122 m	10.9%	≈29.0%
Roman Reach	near St Julians · Casnewydd / Newport	tag: 20% (2026)	sustained	396 m	20 m	5.1%	10.1%
Roman Way	near Caerllion · Casnewydd / Newport	tag: 30% (2021)	sustained	566 m	22 m	3.8%	12.1%
Rosedale Chimney Bank	near Rosedale Abbey · North Yorkshire	100 Climbs¹	sustained	1107 m	149 m	13.4%	26.6%
Route Des Alpes		—	stepped	2169 m	148 m	6.8%	≈31.0%
Ruthin Road	near Gwernymynydd · Sir y Fflint / Flintshire	—	sustained	2228 m	111 m	5.0%	11.3%
Sarn Mellteyrn to Mynydd Rhiw^°	near Sarn Mellteyrn · Gwynedd	—	sustained	1793 m	151 m	8.4%	21.4%
School Street	near Maerdy · Rhondda Cynon Taf	—	sustained	497 m	53 m	10.7%	20.1%
Sennybridge to Yr Allt^°	near Cwm Clydach · Powys	—	sustained	1412 m	56 m	3.9%	≈29.5%
Soar Road	near Talsarnau · Gwynedd	tag: 20% (2026)	sustained	396 m	48 m	12.0%	≈21.5%
Springfield Road	near Maerdy · Rhondda Cynon Taf	—	sustained	410 m	29 m	7.2%	20.0%
Station Road	near Clydach · Sir Fynwy / Monmouthshire	—	sustained	1988 m	221 m	11.1%	≈26.4%
Strada Florida Trailhead (Southernmost) to Pen y Cnwc^°	near Coed Nant-yr-hwch · Powys	—	stepped	2113 m	160 m	7.6%	22.3%
Sunny Bank	near Aberhonddu · Powys	—	sustained	451 m	39 m	8.6%	23.1%
Swansea Road		—	sustained	1815 m	80 m	4.4%	22.3%
Tal-y-bont to Pen-y-gaer^°	near Llanbedr-y-cennin · Conwy	—	sustained	3381 m	335 m	9.9%	23.6%
Tan Yr Allt Avenue	near Mochdre · Conwy	—	stepped	611 m	58 m	9.5%	23.0%
The Conduit	near Trefaldwyn · Powys	—	stepped	743 m	72 m	9.6%	27.5%
The Hendre to Pen-y-lan^°	near The Hendre · Sir Fynwy / Monmouthshire	—	sustained	2447 m	102 m	4.2%	≈26.5%
The Struggle (Kirkstone Road)	near Ambleside · Westmorland and Furness	100 Climbs¹	sustained	1287 m	157 m	12.2%	23.2%
Trallong to Cwm Brynych^°	near Cwm Camlais-fach · Powys	—	sustained	4833 m	160 m	3.3%	24.7%
Tredegar Avenue	near Llanharan · Rhondda Cynon Taf	tag: 20% (2026)	sustained	228 m	21 m	9.4%	16.6%
Trefriw to Llanrhychwyn^°	near Llanrhychwyn · Conwy	—	sustained	2093 m	201 m	9.6%	≈26.9%
Treharris Mountain Road	near Treharris · Merthyr Tudful / Merthyr Tydfil	—	sustained	3562 m	240 m	6.7%	22.0%
Trinity View	near Pilton Vale · Casnewydd / Newport	tag: 40% (2021)	sustained	602 m	80 m	13.3%	≈22.9%
Troed-y-Rhiw Road		—	stepped	2603 m	224 m	8.6%	≈26.3%
Twtil	near Harlech · Gwynedd	tag: 25% (2026)	sustained	352 m	50 m	14.1%	21.5%
Twyn Gof Common to Cwm Dyfnant^°	near Cwm Dyfnant · Powys	—	sustained	2933 m	200 m	6.8%	≈26.4%
Twyn-Garreg-Wen to Cwm Crew^°	near Cwm Crew · Powys	—	sustained	1953 m	78 m	4.0%	10.1%
Ty Canol Lane	near Machen · Caerffili / Caerphilly	—	sustained	2033 m	210 m	10.3%	18.9%
Ty Gwyn Road	near Cwlach · Conwy	tag: 20% (2026)	sustained	841 m	96 m	11.4%	19.4%
Tylwch to Brynposteg Hill^°	near Cwm Jonathan · Powys	—	sustained	4281 m	103 m	2.4%	20.0%
Tylwch to Oldchapel Hill		—	sustained	1916 m	121 m	6.3%	23.8%
Unnamed lane near Llanfihangel-y-Creuddyn		—	stepped	1171 m	114 m	9.7%	≈27.1%
Vine Row	near Ystalyfera · Castell-nedd Port Talbot / Neath Port Talbot	—	sustained	667 m	82 m	12.3%	≈28.5%
Welsh Harp Hollow	near Cwm y Sul · Powys	—	sustained	3695 m	304 m	8.2%	23.1%
Wenallt to Cwm Grognant^°	near Cwm Grognant · Ceredigion	—	sustained	1088 m	86 m	7.9%	≈20.1%
Wern-llaeth to Graig Ddu^°	near Graig Ddu · Ceredigion	—	sustained	558 m	47 m	8.3%	11.5%
Windsor Road	near Six Bells · Blaenau Gwent	—	sustained	448 m	40 m	9.0%	20.4%
Wood Street	near Maerdy · Rhondda Cynon Taf	—	sustained	245 m	29 m	12.0%	20.0%
Woodland Park Road	near Beechwood · Casnewydd / Newport	—	sustained	808 m	60 m	7.4%	23.7%
Wrynose Pass	near Green Crag · Westmorland and Furness	100 Climbs¹	sustained	1028 m	108 m	10.5%	24.6%
Yr Allt		—	sustained	537 m	57 m	10.5%	≈27.8%
Yr Allt	near Allt · Sir Gaerfyrddin / Carmarthenshire	—	sustained	562 m	51 m	9.0%	≈27.8%

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

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