Manning Open Channel Flow Calculator
Velocity and discharge of a rectangular open channel via Manning's equation.
Manning n is the whole game: concrete ≈ 0.013, maintained earth ≈ 0.025, weedy natural channel ≈ 0.035–0.07.
Formula
Manning Open Channel Flow Calculator is a free manning equation for process, mechanical and water engineers — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Manning Open Channel Flow Calculator
Velocity and discharge of a rectangular open channel via Manning's equation. The calculation implements V = (1/n)·R^⅔·S^½, R = A/P (Chow, V.T., Open-Channel Hydraulics, ch. 5). Manning n is the whole game: concrete ≈ 0.013, maintained earth ≈ 0.025, weedy natural channel ≈ 0.035–0.07.
How to use Manning Open Channel Flow Calculator
- 1Enter Channel width in m.
- 2Enter Flow depth in m.
- 3Enter Bed slope (m fall per m run (0.002 = 0.2%)).
- 4Enter Manning n (Concrete 0.013 · earth 0.025 · natural stream 0.035).
- 5Read Discharge, Velocity instantly — no submit button needed.
- 6Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Manning Open Channel Flow Calculator?
- ✓Implements the standard formula — V = (1/n)·R^⅔·S^½, R = A/P
- ✓Reference cited on-page: Chow, V.T., Open-Channel Hydraulics, ch. 5
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Live worked example: the substitution recomputes from your numbers
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Manning Open Channel Flow Calculator use?+
It computes V = (1/n)·R^⅔·S^½, R = A/P, per Chow, V.T., Open-Channel Hydraulics, ch. 5. The formula is displayed under the result along with a worked example substituted with your own inputs.
What should I keep in mind when using this calculator?+
Manning n is the whole game: concrete ≈ 0.013, maintained earth ≈ 0.025, weedy natural channel ≈ 0.035–0.07.
Does this work for any fluid?+
Yes — density and viscosity are inputs (with common fluids suggested in the field hints), so the same physics applies to water, oils, gases and process fluids. Compute always runs in SI internally, so unit mix-ups can't corrupt the result.
Is the Manning Open Channel Flow Calculator free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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