|Length:||3.9 miles (6.3 km)|
|Route outline (key)|
The B4328 is a short B-road in western Carmarthenshire. Except for the section east of Whitland, which follows the pre-bypass route of the A40, the road was originally unclassified, gaining its number in 1935.
The road starts at a roundabout on the Whitland bypass and runs south-westerly along the old route of the A40 into the town itself. Here it turns sharp left to run generally southward before crossing (on the level) the West Wales Line from Carmarthen to Swansea by Whitland railway station and then the River Taf.
The route terminates at a junction with the B4314, just over the Carmarthenshire-Pembrokeshire border at Tavernspite: a place where six roads meet.