Falling Head Permeability Calculator
k of fine soils from the falling-head lab test readings.
Constant-head suits sands (fast flow, measurable volume); falling-head suits silts and clays where you'd wait days for a bucketful. The standpipe IS the flow meter.
Formula
Falling Head Permeability Calculator is a free falling head 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 Falling Head Permeability Calculator
k of fine soils from the falling-head lab test readings. The calculation implements k = 2.303·aL/(A·t)·log₁₀(h₁/h₂) (IS 2720-17; ASTM D5084). Constant-head suits sands (fast flow, measurable volume); falling-head suits silts and clays where you'd wait days for a bucketful. The standpipe IS the flow meter.
How to use Falling Head Permeability Calculator
- 1Enter Standpipe area a in cm².
- 2Enter Sample area A in cm².
- 3Enter Sample length in cm.
- 4Enter Initial head h₁ in cm.
- 5Read Permeability k instantly — no submit button needed.
Why use Falling Head Permeability Calculator?
- ✓Implements the standard formula — k = 2.303·aL/(A·t)·log₁₀(h₁/h₂)
- ✓Reference cited on-page: IS 2720-17; ASTM D5084
- ✓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 Falling Head Permeability Calculator use?+
It computes k = 2.303·aL/(A·t)·log₁₀(h₁/h₂), per IS 2720-17; ASTM D5084. 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 sands (fast flow, measurable volume); falling-head suits silts and clays where you'd wait days for a bucketful. The standpipe IS the flow meter.
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 Falling 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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