About this tool Calculate soil water content (moisture content) from wet and dry mass measurements per BS 1377-2. Enter the mass of the wet specimen and the mass after oven-drying — the tool calculates water content as a percentage of dry mass.
Water content is the most fundamental soil property measured in the laboratory. It is required for Atterberg limit classification, compaction testing, bulk-to-dry density conversion, and phase relationship calculations.
Standard: BS 1377-2:1990, Clause 3 (oven-drying method at 105°C for minimum 24 hours).
How to use this tool 1. Enter the wet mass — mass of the specimen as received, in grams.
2. Enter the dry mass — mass after oven-drying at 105°C to constant mass.
3. Read the water content — expressed as a percentage of dry mass.
Technical information w = (Mw - Md) / Md × 100%
where Mw = wet mass, Md = dry mass. Result is expressed as a percentage of dry mass, not total mass.
Typical values: Sand 5–15% | Silt 15–30% | Clay 20–50% | Organic soil 50–300%+
Limitations The standard oven-drying temperature of 105°C may cause loss of structural water in gypsum-bearing soils or organic breakdown. For gypsiferous soils, use 60°C per BS 1377-2.
Water content can exceed 100% for highly organic soils, peats, and some marine clays. This is physically correct — it means the mass of water exceeds the mass of solids.
Specimens must be tested promptly after sampling. Moisture loss during transport and storage will give unrepresentative results.
Revision history 2 April 2026: Content update and publish
11 January 2026: Initial release
Disclaimer This tool is provided for educational and general information purposes only. It is not a substitute for professional engineering advice, design or verification.
Diggy and its contributors are not licensed engineering consultants and no results generated by this tool should be used directly for construction, design or safety-critical decisions.
All values and outputs are based on published empirical correlations and should be independently checked and confirmed by a qualified geotechnical engineer before use.
By using this tool, you accept full responsibility for how you interpret and apply the information provided.
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