Calculator Input
Use the multi-point Casagrande method. Enter at least two complete trials. The form uses a three-column large-screen layout, two-column medium layout, and one-column mobile layout.
Formula Used
The calculator uses the multi-point liquid limit procedure based on the flow curve. Water content is calculated for each trial, then a straight line is fitted between water content and the logarithm of blows.
Water mass: Mw = Ww − Wd
Dry soil mass: Md = Wd − Wc
Water content: w = (Mw / Md) × 100
Flow curve: w = m × log10(N) + c
Liquid limit: LL = m × log10(25) + c
Here, Ww is wet mass plus container, Wd is dry mass plus container, Wc is container mass, N is blow count, m is slope, and c is intercept.
How to Use This Calculator
- Prepare at least two, and preferably three or four, moisture trials.
- Enter the blow count for each trial from the liquid limit device.
- Enter wet mass, dry mass, and empty container mass in grams.
- Click Calculate Liquid Limit to compute water contents and the fitted flow curve.
- Review the liquid limit at 25 blows, slope, intercept, and R².
- Use the CSV or PDF button to export the output for reporting.
Example Data Table
This example demonstrates a typical multi-point test set. You can load these values into the calculator using the example button.
| Trial | Blows | Wet Mass (g) | Dry Mass (g) | Container Mass (g) | Water Content (%) |
|---|---|---|---|---|---|
| 1 | 18 | 26.83 | 22.20 | 12.40 | 47.245 |
| 2 | 24 | 26.16 | 22.05 | 12.50 | 43.037 |
| 3 | 31 | 25.80 | 21.96 | 12.35 | 39.958 |
| 4 | 42 | 25.38 | 21.90 | 12.45 | 36.825 |
Frequently Asked Questions
1. What is liquid limit in soil engineering?
Liquid limit is the water content at which a fine-grained soil changes from plastic behavior to liquid behavior under a standard laboratory procedure.
2. Why is the result taken at 25 blows?
The standard Casagrande liquid limit method defines liquid limit as the water content corresponding to 25 blows on the fitted flow curve.
3. How many trials should I enter?
Use at least two complete trials to calculate a line, but three or four trials provide a more dependable flow curve and a better quality check.
4. Can this page be used for a one-point method?
This page is designed for multi-point flow curve evaluation. A dedicated one-point method uses correction factors and should be treated separately.
5. Why must dry mass be greater than container mass?
Dry soil mass equals dry mass minus container mass. If dry mass is not greater, the soil mass becomes zero or negative and the result is invalid.
6. What does R² show in the result?
R² indicates how well the fitted line represents the entered data. Values closer to 1 suggest the points follow a consistent flow curve.
7. Which units should I use for mass?
Use the same mass unit throughout the test. Grams are standard in the laboratory and are used in the example data.
8. Does the calculator classify the soil completely?
No. It gives an indicative plasticity band from liquid limit only. Full soil classification also needs plastic limit and other index data.