It runs from Swansea in Wales to Chester in England via Llandovery, Llandrindod Wells, Oswestry and Wrexham, a distance of around 153 miles (246 km).

The original route, through the centre of the town, passed under the Cambrian Line at the Dolfor Road Railway Bridge.

A bypass to the Southeast of Newtown was opened in 2019, crossing the Cambrian Line to the East of the town before rejoining the original route.

From Newtown, the road continues to Welshpool, running roughly parallel to the River Severn, before crossing the border into England at Llanymynech.

There have been demands for a dual carriageway from Shrewsbury to Wrexham, including the section of the A483 from Oswestry to Ruabon; also a campaign by residents for a bypassing Llanymynech and Pant.