Atterberg Limits (LL, PL, PI)
Liquid limit from the flow curve at 25 blows, plastic limit, plasticity index and soil class (CL, CH, ML, MH) from the plasticity chart.
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About this test
Enter your Casagrande-cup trials and plastic-limit threads. The sheet fits the flow curve, reads the liquid limit at 25 blows, works out the plasticity index and places the soil on the plasticity chart.
How it's calculated
- LL = moisture content at 25 blows on the best-fit line of w vs log N
- PI = LL − PL
- A-line: PI = 0.73 (LL − 20); above → clay (C), below → silt (M); LL ≥ 50 → high plasticity (H)
Results are calculated from the values you enter using standard formulas. Download the PDF to keep a record. For certified testing, design or construction, talk to our engineers.
Kataria Engineering & Consultancy Services (2026). Atterberg Limits (LL, PL, PI) [online calculator]. https://katariaengineering.com/tools/atterberg-limits-test.html
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