Over the Prince of Wales Bridge the M4 crosses into Wales at junction 23 and runs for about 68 miles past Newport, Cardiff, Bridgend, Port Talbot and Swansea to its end at Pont Abraham, junction 49, where the A48 carries on west towards Carmarthen.

National Highways’ live data covers the M4 in England only, so this map shows the road, the junctions and the towns in Wales, but no live speeds. We do not have live speed flow for the M4 in Wales at the moment; we hope to be able to show it at some point.

The M4 in Wales is split into three sections, shown as dashed boxes. Tap a box, or one of the sections below the map, for a closer map with the distances and times junction by junction. Tap a junction number to open that junction’s own page.

The Three M4 Sections in Wales

• Section 5 · J23–J33
  Newport and Cardiff
• Section 6 · J33–J42
  Bridgend and Port Talbot
• Section 7 · J42–J49
  Swansea to Pont Abraham