It begins at the Isle of Grain and runs in a south-westerly direction to connect eventually with the A21 trunk road at Pembury.

The most influential force on the recent upgrading of the road has been the development of Kings Hill near West Malling.

Passing High Halstow and turning south, it follows Sharnal Street which then becomes the Ratcliffe Highway, which bypasses Hoo St Werburgh and skirts the Deangate Ridge Golf Club.

Continuing south, the road passes over the M2 and High Speed 1 on Sundridge Hill where those two routes reach land again after crossing their respective Medway bridges.

Passing Manor Park Country Park to the west and the roundabout at the northern entrance to Kings Hill, the road becomes Ashton Way before meeting the Malling Road at the southern tip of West Malling and proceeding through Mereworth.