Constant Head Permeability Calculator
Coefficient of permeability k from the constant-head lab test — the standard for sands and gravels.
Constant head suits k > 10⁻⁴ cm/s (clean sands); below that the flow is too slow to collect meaningfully — switch to the falling-head test. Clean gravel runs ~1 cm/s, silty sand ~10⁻⁴.
Formula
Constant Head Permeability Calculator is a free constant head permeability test for geotechnical engineers and foundation designers — 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 Constant Head Permeability Calculator
Coefficient of permeability k from the constant-head lab test — the standard for sands and gravels. The calculation implements k = QL ÷ (A·h·t) (IS 2720 Part 17; ASTM D2434). Constant head suits k > 10⁻⁴ cm/s (clean sands); below that the flow is too slow to collect meaningfully — switch to the falling-head test. Clean gravel runs ~1 cm/s, silty sand ~10⁻⁴.
How to use Constant Head Permeability Calculator
- 1Enter Water collected in mL.
- 2Enter Sample length in mm.
- 3Enter Sample cross-section area in cm².
- 4Enter Constant head difference in mm.
- 5Read Permeability k, In m/s instantly — no submit button needed.
- 6Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Constant Head Permeability Calculator?
- ✓Implements the standard formula — k = QL ÷ (A·h·t)
- ✓Reference cited on-page: IS 2720 Part 17; ASTM D2434
- ✓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 Constant Head Permeability Calculator use?+
It computes k = QL ÷ (A·h·t), per IS 2720 Part 17; ASTM D2434. 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?+
Constant head suits k > 10⁻⁴ cm/s (clean sands); below that the flow is too slow to collect meaningfully — switch to the falling-head test. Clean gravel runs ~1 cm/s, silty sand ~10⁻⁴.
Can this replace a soil investigation?+
No calculator replaces boreholes and lab tests — but with investigated parameters in hand, this gives you the standard-method result instantly, with the formula shown so reviewers can check it.
Is the Constant Head Permeability 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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