|Location Map ( geo)|
|Distance:||10.3 miles (16.6 km)|
|Meets:||B3143, A352, C19 (Dorset)|
|Route outline (key)|
The C12 starts at a junction with the B3143 on the outskirts of Dorchester. It climbs the Dorset Downs, passing Charminster and Charlton Down, before reaching a junction with the C19, which rejoins the B3143 (which follows the Piddle Valley). The C12 continues down a steep descent, before joining the A352 near Middlemarsh.