Compare calculators
Both calculators run independently β change the inputs on either side to compare results.
Civil
Culvert Flow Calculator
Calculate the full-flow discharge capacity of a circular culvert using Manning's equation. Used by drainage engineers to check whether an existing or proposed culvert can pass a design flood without overtopping.
Fill in the required fields to see your result.
Civil
Culvert Sizing Calculator
Calculate the required culvert diameter to safely pass design stormwater flows under roads, driveways, or embankments. Helps engineers and contractors avoid undersized culverts that cause flooding or washouts.
Fill in the required fields to see your result.
Key differences
| Culvert Flow Calculator | Culvert Sizing Calculator | |
|---|---|---|
| Category | Civil | Civil |
| Inputs required | 4 | 4 |
| Result | Flow Rate (cfs) | Required Culvert Diameter (inches) |
| What it does | Calculate the full-flow discharge capacity of a circular culvert using Manning's equation. Used by drainage engineers to check whether an existing or proposed culvert can pass a design flood without overtopping. | Calculate the required culvert diameter to safely pass design stormwater flows under roads, driveways, or embankments. Helps engineers and contractors avoid undersized culverts that cause flooding or washouts. |