| Road | From | To | Notes |
|---|
| A4 | Central London | Avonmouth | |
| A40 | Central London | Fishguard | |
| A41 | Central London | Birkenhead | |
| A42 | Appleby Magna | Diseworth | |
| A43 | M40 motorway Junction 10 north of Bicester | Stamford | |
| A44 | Oxford | Aberystwyth | Officially the most dangerous road in Wales between Aberystwyth and Llangurig. |
| A45 | Birmingham | Near Thrapston | |
| A46 | Bath | Cleethorpes | |
| A47 | Birmingham | Great Yarmouth | |
| A48 | Highnam near Gloucester | Carmarthen | Originally began in Worcester. Worcester to Newport is now A449. |
| A49 | Ross-on-Wye | Bamber Bridge | |
| A400 | Victoria Embankment | Archway | |
| A401 | Piccadilly Circus | Islington | |
| A402 | Marble Arch | Chiswick | |
| A403 | M48 motorway Junction 1 near Aust | Avonmouth | |
| A404 | Paddington | Maidenhead | |
| A405 | Leavesden Green | Near Park Street | |
| A406 | Gunnersbury | Beckton | This is the North Circular Road |
| A407 | Harlesden | Child's Hill | |
| A408 | Harmondsworth | Uxbridge | |
| A409 | Northwick Park Hospital | Bushey | |
| A410 | Pinner | Edgware | |
| A411 | Watford | Barnet | |
| A412 | Slough | Watford | |
| A413 | Gerrards Cross | Towcester | |
| A414 | Near Hemel Hempstead | Maldon | |
| A415 | Berinsfield | Witney | |
| A416 | Amersham | Berkhamsted | |
| A417 | Streatley | Leominster | |
| A418 | Tiddington | Ascot | |
| A419 | Whitminster | Swindon | |
| A420 | Bristol | Oxford | |
| A421 | Brackley | St Neots | |
| A422 | Bedford | Worcester | Concurrent with the A46 between Stratford-upon-Avon and Alcester |
| A423 | Hinksey Hill | Coventry | Small section of the road is part of the Oxford Ring Road. Reprised at Banbury. | |
| A424 | Burford | A44 near Bourton-on-the-Hill | |
| A425 | Daventry | Warwick | |
| A426 | Leicester | Southam | |
| A427 | Market Harborough | Oundle | |
| A428 | Coventry | Cambridge | |
| A429 | Chippenham | Coventry | |
| A430 | Quedgeley | Longford, Gloucester | |
| A431 | Bristol | Bath | |
| A432 | Bristol | Old Sodbury | |
| A433 | A46 at Dunkirk | A429 SW of Cirencester | |
| A434 | Defunct | | Used to run from Malmesbury to Hardwicke | |
| A435 | Birmingham | Cirencester | Concurrent with the A46 between Alcester and Teddington Hands | |
| A436 | A417 near Brockworth | A44 near Salford | |
| A437 | Hamondsworth | A40 Western Avenue | Originally Gloucester to Newport, now A48. |
| A438 | M5 motorway Junction 9 | Llanfilo | |
| A439 | Stratford-upon-Avon | A46 4 miles SW of Warwick | |
| A440 | Defunct | | Used to run from Pershore to Great Malvern | |
| A441 | Birmingham | Cookhill | |
| A442 | Droitwich | Whitchurch | |
| A443 | Worcester | Newnham Bridge | |
| A444 | Baginton | Burton upon Trent | |
| A445 | Warwick | A45 at Ryton-on-Dunsmore | |
| A446 | Little Packington | Roughley | |
| A447 | Hinckley | Coalville | |
| A448 | Kidderminster | Studley | |
| A449 | Newport | Stafford | |
| A450 | Torton | West Hagley | |
| A451 | Stourbridge | Great Witley | |
| A452 | Leamington Spa | Brownhills | |
| A453 | Nottingham | Birmingham | |
| A454 | Bridgnorth | Four Oaks | |
| A455 | Defunct | | Used to run from M4 junction 24 in Ringland, Newport to George Street Bridge. Most is now part of the A48 Southern Distributor Road |
| A456 | Birmingham | Woofferton | |
| A457 | Birmingham | Sedgley | |
| A458 | Mallwyd | Quinton | |
| A459 | Spring Hill | Wolverhampton | |
| A460 | Wolverhampton | Rugeley | |
| A461 | Lichfield | Stourbridge | |
| A462 | Wednesbury | Laney Green | |
| A463 | Wombourne | Willenhall | |
| A464 | Oaken | Hollinswood | |
| A465 | Hereford | M4 motorway | |
| A466 | Kingsthorne | Chepstow | |
| A467 | Duffryn, Newport | A465, Brynmawr | |
| A468 | Bassaleg, Newport | A470, Nantgarw | |
| A469 | A4161, Roath, Cardiff | A465, Rhymney | |
| A470 | Cardiff | Llandudno | |
| A471 | Defunct | | Used to run from Usk to Abergavenny |
| A472 | Treharris | Usk | |
| A473 | Pontypridd | Bridgend | |
| A474 | Briton Ferry | Ammanford | |
| A475 | Newcastle Emlyn | Lampeter | |
| A476 | Llanelli | Llandeilo | |
| A477 | St Clears | Johnston | |
| A478 | Cardigan | Tenby | |
| A482 | Aberaeron | Llandovery | |
| A483 | Swansea | Chester | |
| A484 | Cardigan | Cadle near Swansea | by way of Newcastle Emlyn, Carmarthen and Llanelli |
| A485 | Tanerdy | Llanfarian | |
| A487 | Haverfordwest | Bangor | |
| A488 | Penybont | Shropshire | |
| A491 | Lydiate Ash | Wall Heath | |
| A493 | Machynlleth | Dolgellau | Via Tywyn | |
| A494 | Queensferry | Dolgellau | |
| A495 | Whitchurch | Oswestry | |
| A496 | Llanelltyd | Blaneau Ffestiniog | Via Barmouth | |
| A497 | Porthmadog | Nefyn | |
| A498 | Pen-y-Gwryd | Porthmadog | |
| A499 | A487 | Abersoch | |
| A4000 | Acton Town | Harlesden | |
| A4006 | Harrow | Kenton | Also known as Kenton Road |
| A4008 | Hatch End | Watford | |
| A4012 | Husborne Crawley | A4146 | |
| A4018 | Bristol | Cribbs Causeway | |
| A4019 | Coombe Hill | Cheltenham | |
| A4020 | Shepherds Bush | Denham | |
| A4025 | Stourport-on-Severn | A449 | |
| A4032 | Bristol | Bristol | |
| A4033 | Dudley | West Bromwich | |
| A4034 | Quinton | West Bromwich | |
| A4037 | Wednesbury | Dudley | |
| A4040 | | | Birmingham Outer ring road |
| A4042 | Abergavenny | A48, Newport | |
| A4043 | Blaenavon B4246 | Pontypool, A472 | |
| A4044 | Redcliffe | Bristol | |
| A4046 | A465, Rassau | A467, Aberbeeg | |
| A4047 | A4048, Tredegar | A465, Brynmawr | |
| A4048 | A467, Crosskeys | A465, Tredegar | |
| A4049 | A4048, Pontllanfraith | A469, New Tredegar | |
| A4050 | A4232, Culverhouse Cross, Cardiff | A4055, Barry | |
| A4051 | Newport | North Cwmbran | |
| A4053 | | | Coventry Ring Road |
| A4054 | A4119, Llandaff, Cardiff | A470, Cefn-Coed-y-Cymmer | |
| A4055 | A4232, Llandough, Cardiff | Barry Island, Barry | |
| A4058 | A473, Glyntaff | A4061, Treorchy | |
| A4059 | A470, Abercynon | A470, Between Brecon and Cefn-Coed-y-Cymmer | |
| A4060 | A470, Pentrebach | A465, Dowlais Top | |
| A4061 | Bridgend | Hirwaun | |
| A4067 | Swansea | Sennybridge | |
| A4071 | Dunsmore Heath | Rugby | |
| A4072 | M4, Junction 28, Newport | A467, Bassaleg (concurrent with A467) | |
| A4074 | Iffley | Caversham | Links Reading with Oxford |
| A4080 | Menai Bridge | Engedi | |
| A4085 | Minffordd | Caernarfon | |
| A4086 | Capel Curig | Caernarfon | |
| A4087 | Bangor | Bangor | |
| A4088 | Willesden | Neasden | |
| A4090 | Wembley | North Harrow | |
| A4094 | Loudwater | Maidenhead | |
| A4097 | Bangor | Bangor | |
| A4101 | Kingswinford | Dudley | |
| A4102 | Amblecote | | English version |
| A4102 | Merthyr Tydfil | Merthyr Tydfil | Welsh version - Located in the Town Centre |
| A4103 | Worcester | Hereford | |
| A4107 | Bwlch y Clawdd | Port Talbot | |
| A4112 | Tenbury Wells | Eardisley | |
| A4113 | Ludlow | Knighton | |
| A4114 | Allesley | Willenhall | |
| A4117 | Near Bewdley | Cleehill | |
| A4119 | Ystrad | Cardiff Bay | |
| A4120 | Llanbadarn Fawr, Aberystwyth | Ponterwyd | It runs parallel with the A44, but on the other side of the Rheidol Valley. |
| A4123 | Wolverhampton | Birmingham | |
| A4124 | Wolverhampton | Brownhills | |
| A4127 | Heston | Wembley | |
| A4130 | Burchetts Green | Rowstock | The section of road between Milton Hill and Rowstock was formerly part of the A34. |
| A4133 | Great Witley | Droitwich Spa | |
| A4137 | Marston | St Owen's Cross | |
| A4138 | Pontardulais | Llanelli | |
| A4140 | Wembley | Bushey Heath | |
| A4141 | Bristol | Five Ways | |
| A4142 | Heyford Hill, Oxford | Headington | Part of the Oxford Ring Road |
| A4144 | Pear Tree | Redbridge Park and Ride | |
| A4145 | Watford | Rickmansworth | |
| A4146 | Milton Keynes | Hemel Hempstead | |
| A4147 | Hemel Hempstead | St Albans | |
| A4150 | | | Wolverhampton Ring Road |
| A4155 | Bourne End | Reading | |
| A4158 | Oxford | Iffley | |
| A4159 | Bow Street, Aberystwyth | A44 | Acts as a by-pass around the northern part of Aberystwyth. |
| A4160 | Newport Road, Cardiff | Penarth | |
| A4161 | Ely Bridge, Cardiff | Southern Way, Cardiff | Runs along a part of the old A48 |
| A4165 | Oxford | Kidlington | Banbury Road |
| A4167 | Birmingham | A456 | |
| A4172 | Preston Cross | Trumpet | |
| A4173 | Stroud | Gloucester |
| A4174 | Bristol | Bristol | The Avon Ring Road |
| A4175 | Hicks Gate | Soundwell | |
| A4180 | Yeading | Northwood | |
| A4183 | Abingdon | Lodge Hill | Oxford Road, Abingdon. This road was formerly part of the A34. The remaining part of the road between Lodge Hill and Hinksey Hill near Oxford has since been unclassified. |
| A4185 | Rowstock | Chilton | This road was formerly part of the A34. |
| A4200 | Aldwych | Camden Town | |
| A4201 | Aldwych | Camden Town | |
| A4202 | Hyde Park Corner | Marble Arch | Park Lane, part of the London Inner Ring Road |
| A4208 | Ludgate Circus | Holborn Circus | |
| A4212 | Bala | Trawsfynydd | |
| A4229 | Pyle | Porthcawl | |
| A4232 | M4 Junction 30 Cardiff East | M4 Junction 33 Cardiff West | Cardiff Link Road (Peripheral Distribution Road) |
| A4234 | Adam Street, Cardiff | Queensgate Roundabout, Cardiff | Central Link Road of the Peripheral Distribution Road |
| A4244 | Brynrefail | Glasinfryn | Reclassified from parts of B4366 and B4547 |
| A4251 | Kings Langley | Near Tring | |
| A4252 | West Bromwich | Smethwick | |
| A4259 | Swindon | Wanborough | |
| A4260 | Near Pear Tree | Banbury | |
| A4289 | Swindon | Swindon | |
| A4303 | Cross in Hand | Junction 20 of M1 | |
| A4304 | Junction 20 of M1 | Market Harborough | |
| A4311 | Swindon | Swindon | |
| A4312 | Swindon | Swindon | |
| A4135 | Tetbury | Near M5 motorway | |
| A4320 | Arno's Vale | M32 Junction 3 | |
| A4400 | | | Birmingham Inner Ring Road |
| A4440 | Worcester | Worcester | |
| A4500 | Northampton | Wellingborough | formerly A45 |
| A4535 | Kidderminster | Kidderminster | |
| A4536 | Fernhill Heath | A38 | |
| A4538 | Spetchley | Martin Hussingtree | |
| A4540 | | | Birmingham Middle Ring Road |
| A4600 | M69 Junction 2 | Coventry | |
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