Culvert Calculator

Estimate culvert pipe length, gravel bedding and backfill volume, and geotextile fabric area for a rural driveway crossing. Planning estimate only.

Common questions

What size culvert pipe do I need for a driveway crossing?: Diameter is set by the drainage area feeding the crossing, not by driveway width. Undersized pipe backs water up and washes the shoulders. Length is set by driveway width plus the fill slope on both ends, which this calculator computes for you.
How much cover do I need over a culvert pipe?: Most plastic and metal pipe manufacturers call for a minimum of 12 in of compacted cover over the crown for vehicle traffic, more for heavy equipment. Less cover is the most common cause of crushed pipe.
Do I need a permit to install a driveway culvert?: Where the driveway meets a public road, almost always. Counties usually specify diameter, end treatment, and inlet elevation. Check before ordering pipe — the required size may be larger than your own estimate.