Pipe & Channel Flow: Manning's Calculator

Manning's and Hazen-Williams calculator: normal depth, pipe sizing, required slope, critical depth and Froude, offline.

The pipe and open-channel calculator that lives in your toolbar and works offline. FREE, FOREVER • Flow at depth: Q, V, A, P, R, top width, Froude number and critical depth for circular pipes, rectangular, trapezoidal and triangular channels • Depth ratio, full-flow capacity and percent of capacity for pipes • Pressure pipe (Hazen-Williams): head loss, psi drop, loss per 1,000 ft and velocity • Manning's n picker with 27 materials (Chow's Open-Channel Hydraulics) and C factors for common pipe PRO, $2.99 ONCE (free for your first 7 days) • Normal depth for any discharge, with a clear "surcharged" result when a pipe can't carry it as open-channel flow • Smallest standard pipe size for a design flow, with an optional maximum depth ratio (for example y/D ≤ 0.8) • Required slope to carry a flow at a given depth or flowing full • Copy a clean results block into your calcs, email or report DETAILS ENGINEERS CARE ABOUT • Circular pipes handle the region between full flow and maximum flow (y/D ≈ 0.94) correctly • Warnings for velocities below self-cleansing limits and Froude numbers near 1 • US (ft, cfs, gpm, in) and SI (m, m³/s, mm). Switching units converts your inputs • Checked against hand calculations: a 24-in RCP at n 0.012 and 0.30% carrying 6.8 cfs gives 4.3 ft/s PRIVACY No data leaves your computer. No tracking, no ads, no account. The only network call is the optional payment check through ExtensionPay. Results assume steady, uniform flow. Check them against your local design criteria.