Hydraulic Gradient Calculator
Head loss per unit length between two gauges — slope of the hydraulic grade line.
Water mains are typically designed for gradients of 0.001–0.01 (0.1–1 m per 100 m). If the HGL dips below the pipe, you have sub-atmospheric pressure.
Formula
Hydraulic Gradient Calculator is a free hydraulic gradient 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 Hydraulic Gradient Calculator
Head loss per unit length between two gauges — slope of the hydraulic grade line. The calculation implements i = Δh / L (AWWA M11 / Mays, Water Distribution Systems Handbook). Water mains are typically designed for gradients of 0.001–0.01 (0.1–1 m per 100 m). If the HGL dips below the pipe, you have sub-atmospheric pressure.
How to use Hydraulic Gradient Calculator
- 1Enter Upstream head in m.
- 2Enter Downstream head in m.
- 3Enter Pipe length between gauges in m.
- 4Read Hydraulic gradient, Head loss per 100 m instantly — no submit button needed.
- 5Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Hydraulic Gradient Calculator?
- ✓Implements the standard formula — i = Δh / L
- ✓Reference cited on-page: AWWA M11 / Mays, Water Distribution Systems Handbook
- ✓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 Hydraulic Gradient Calculator use?+
It computes i = Δh / L, per AWWA M11 / Mays, Water Distribution Systems Handbook. 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?+
Water mains are typically designed for gradients of 0.001–0.01 (0.1–1 m per 100 m). If the HGL dips below the pipe, you have sub-atmospheric pressure.
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 Hydraulic Gradient 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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