Critical Depth Calculator (Rectangular Channel)
Critical depth, velocity and minimum specific energy for a rectangular channel.
Flow passes through critical depth at free overfalls and weir crests — measure depth there and you know the discharge.
Formula
Critical Depth Calculator (Rectangular Channel) is a free critical depth 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 Critical Depth Calculator (Rectangular Channel)
Critical depth, velocity and minimum specific energy for a rectangular channel. The calculation implements y_c = (q²/g)^⅓; E_min = 1.5·y_c (Chow, Open-Channel Hydraulics, ch. 4). Flow passes through critical depth at free overfalls and weir crests — measure depth there and you know the discharge.
How to use Critical Depth Calculator (Rectangular Channel)
- 1Enter Discharge in m³/s.
- 2Enter Channel width in m.
- 3Read Critical depth, Critical velocity, Min specific energy instantly — no submit button needed.
- 4Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Critical Depth Calculator (Rectangular Channel)?
- ✓Implements the standard formula — y_c = (q²/g)^⅓; E_min = 1.5·y_c
- ✓Reference cited on-page: Chow, Open-Channel Hydraulics, ch. 4
- ✓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 Critical Depth Calculator (Rectangular Channel) use?+
It computes y_c = (q²/g)^⅓; E_min = 1.5·y_c, per Chow, Open-Channel Hydraulics, ch. 4. 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?+
Flow passes through critical depth at free overfalls and weir crests — measure depth there and you know the discharge.
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 Critical Depth Calculator (Rectangular Channel) 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.
Related Engineering tools
Reynolds Number Calculator
Compute Re from density, velocity, pipe diameter and viscosity — with instant laminar/turbulent classification.
● LiveLaminar vs Turbulent Flow Classifier
Classify hydraulic-oil or process-fluid flow regime from kinematic viscosity, line velocity and tube bore.
● LiveBernoulli Equation Solver
Solve downstream pressure between two points from velocities, elevations and fluid density (ideal, lossless).
● Live