The road measures 17.65 miles long and would take a car obeying speed limits 33 minutes to travel its length.
The B645 is a B Road and is located in the Zone 6 Highways Region.
This is a true long-distance route, journeying through numerous towns like RUSHDEN, Higham Ferrers, Chelveston, Caldecott, Hargrave, Lower Dean, Tilbrook, Kimbolton, Spaldwick, Stonely, Great Staughton, Hail Weston, and Eaton Ford.
The road passes through several counties, including Northamptonshire, Bedfordshire, and Cambridgeshire.