Culvert Sizing Calculator

Calculate culvert size for roadway drainage.

Rate of fluid movement through the system.
cfs
Proportional relationship between two values.
Angle of incline, often as ratio or percentage.
%
Linear measurement in the specified unit.
ft

Results

Culvert Diameter:
Calculated culvert diameter based on your inputs.
-in
Headwater Depth:
Calculated headwater depth based on your inputs.
-ft
Outlet Velocity:
Calculated speed or velocity.
-ft/s
Reference: AWWA/EPA Standards. FHWA HDS-5.