The road measures 15.40 miles long and would take a car obeying speed limits 24 minutes to travel its length.
The A4120 is a A Road and is located in the Zone 4 Highways Region.
This is a true long-distance route, journeying through numerous towns like Penparcau, Llanbadarn Fawr, Southgate, Capel Seion, Pisgah, Devils Bridge, Llanddewi Brefi, and Ponterwyd.
The road connects Dyfed and Dyfed.