Culvert Flow Calculator vs Culvert Sizing Calculator
Two calculators for the same neighbourhood of questions. Here is what each measures, what you feed in, and where you'd reach for one over the other.
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.
- Answers
- Flow Rate (cfs)
- Inputs
- Culvert Diameter, Culvert Slope, Manning's Roughness, Flow Depth Ratio
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.
- Answers
- Required Culvert Diameter (inches)
- Inputs
- Drainage Area, Design Rainfall, Runoff Coefficient, Culvert Slope
At a glance
| Culvert Flow Calculator | Culvert Sizing Calculator | |
|---|---|---|
| Category | Civil | Civil |
| Answers | Flow Rate | Required Culvert Diameter |
| Inputs | 4 | 4 |
| Result unit | cfs | inches |
When to use each
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.