Calculator Inputs
Formula Used
Measured weight basis formula:
w = ((Wsat - Wdry) / Wdry) × 100
With container correction:
Wdry = dry sample with container - container weight
Wsat = saturated sample with container - container weight
Phase relationship formula:
w = (S × e / Gs) × 100
Where w is water content by weight. Wsat is saturated soil weight. Wdry is oven dry soil weight. S is saturation as a decimal. e is void ratio. Gs is specific gravity of soil solids.
How to Use This Calculator
- Select the measured method when wet and dry sample weights are available.
- Enter container tare weight if your sample was weighed in a pan.
- Select the theoretical method when void ratio and specific gravity are known.
- Enter sample volume if unit weight output is needed.
- Add project moisture limits when you want a quick range check.
- Press the calculate button to show results above the form.
- Use CSV or PDF export for records and reports.
Example Data Table
| Sample | Wet + Container | Dry + Container | Container | Water Weight | Dry Soil Weight | Water Content |
|---|---|---|---|---|---|---|
| Backfill A | 2.85 kg | 2.42 kg | 0.30 kg | 0.43 kg | 2.12 kg | 20.28% |
| Subgrade B | 3.40 kg | 2.90 kg | 0.35 kg | 0.50 kg | 2.55 kg | 19.61% |
| Borrow Soil C | 4.10 kg | 3.42 kg | 0.40 kg | 0.68 kg | 3.02 kg | 22.52% |
Why Saturated Soil Weight Checks Matter
Saturated soil weight testing helps builders understand how much water a soil sample holds at full saturation. The value supports earthwork, backfill, slope, drainage, and foundation decisions. A saturated soil can gain mass quickly. That added mass changes handling, compaction, settlement risk, and lateral pressure. Weight basis reporting is direct because it compares water weight with dry soil weight.
Construction Use
Field teams often collect a wet saturated sample, dry it, and compare both weights. The calculator accepts those measurements with or without a container weight. It also supports a theoretical method using void ratio, specific gravity, and degree of saturation. This helps when lab data includes phase relationship values instead of raw wet and dry weights.
Reading the Output
The main result is saturated water content by weight. It is shown as a percentage and as a decimal ratio. The tool also reports water weight, dry soil weight, saturated total weight, and optional theoretical values. These figures help compare samples from borrow pits, trench bottoms, compacted fills, and stockpiles. High values may indicate poor drainage, organic content, or large void spaces.
Better Field Decisions
Moisture affects construction performance. Soil near saturation may pump under equipment. It may fail density tests. It may also lose shear strength during excavation or loading. Knowing the weight basis value helps decide whether to aerate, blend, replace, compact, or delay work. The result should be reviewed with project specifications and geotechnical recommendations.
Good Measurement Practice
Use calibrated scales. Record units clearly. Remove loose debris before weighing. Dry the sample until its mass becomes stable. When a container is used, weigh it separately and subtract it from wet and dry readings. For theoretical checks, use reliable values for specific gravity and void ratio. Small measurement errors can change the final percent, especially for light samples.
Reporting
The export buttons create simple records for daily logs and lab notes. Keep the sample source, date, and method with each result. Consistent reporting makes later comparison easier. Store the calculation beside density results, Proctor targets, and inspection comments. When conditions change after rain or dewatering, run another check on site. A fresh value gives supervisors a clearer view of material readiness too.
FAQs
What does saturated soil on a weight basis mean?
It means the water held in the saturated soil is compared with the dry soil weight. The result is usually shown as a percentage.
Which weight should I enter as wet weight?
Enter the weight of the saturated sample before oven drying. If it was weighed inside a container, include the container weight and enter the tare separately.
Why is oven dry weight needed?
Oven dry weight represents the solid soil weight after removing moisture. It is the base value used for weight basis water content.
Can I use grams instead of kilograms?
Yes. Any consistent weight unit works because the main result is a ratio. Use the same unit for all weight entries.
What is the theoretical method for?
It estimates water content using void ratio, specific gravity, and saturation. Use it when phase relationship data is available.
What does void ratio mean?
Void ratio compares void volume with solid volume. Higher void ratio often means the soil can hold more water at saturation.
Why add sample volume?
Sample volume lets the calculator estimate saturated bulk unit weight and dry unit weight. This is useful for construction records.
Is this a replacement for lab testing?
No. It supports calculations and reporting. Use approved field or laboratory procedures for project acceptance decisions.