Circular Culvert Geometry

Compute hydraulic radius, wetted perimeter, and area


Circular culvert geometry calculation is mobile-device-friendly as of August 4, 2014

Select calculation: 
Diameter, d (L): 
© 2014 LMNO Engineering, Depth, y (L): 
Research, and Software, Ltd. Top Width, T (L): Area, A (L2): 
Wetted Perimeter, P (L): 
Hydraulic Radius, R (L): 
Angle, θ (degrees): 

Units in culvert geometry calculator: You may enter numbers in any units, so long as you are consistent. (L) means that the variable has units of length (e.g. meters). (L2) means that the variable has units of length squared (e.g. m2). For instance, enter d, y, and T all in meters or all in inches or all in feet.

Diagram and Equations for culvert geometry calculator:

Circular Culvert Geometry

Top width, T, is the top width of the water in the pipe. T=0 if the pipe is empty or full. T=d if the pipe is half full.

Culvert Geometry Equations

The circular culvert geometry calculation does not check for unreasonable inputs. Please enter 0<y<d, 0<T<d, and d>0.


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Please contact us for consulting or other questions.

LMNO Engineering, Research, and Software, Ltd.
7860 Angel Ridge Rd.   Athens, Ohio 45701  USA   Phone and fax: (740) 592-1890


LMNO Engineering home page (more calculations)  

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Other information:


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