Enter masses, choose method, and compute moisture percentage fast with clear units. Optional batch correction shows water adjustments for stronger pours every single time.
Oven-dry basis: MC (%) = (Mw − Md) / Md × 100
Wet basis: MCw (%) = (Mw − Md) / Mw × 100
Where Mw is wet mass and Md is dry mass after oven drying to constant weight.
| Sample | Material | Wet (Mw) | Dry (Md) | Oven-dry MC (%) | Wet-basis MCw (%) |
|---|---|---|---|---|---|
| A-01 | Aggregate | 2.650 | 2.500 | 6.000 | 5.660 |
| T-07 | Timber | 1.120 | 0.980 | 14.286 | 12.500 |
| S-12 | Soil | 0.540 | 0.450 | 20.000 | 16.667 |
| M-03 | Masonry | 3.040 | 2.950 | 3.051 | 2.961 |
| I-09 | Insulation | 0.310 | 0.280 | 10.714 | 9.677 |
Moisture content compares the water in a material to its dry solids. In field terms, you weigh the sample before drying (wet mass) and after oven drying to constant mass (dry mass). The percentage can be reported on an oven‑dry basis or on a wet basis, depending on your site practice.
Uncontrolled moisture shifts mix water, changes workability, and increases variability. For concrete, wet aggregate can silently add water and weaken strength if the mix design water is not reduced. For timber, excess moisture promotes shrinkage, warping, and fastener loosening as the member equilibrates after installation.
Moisture checks are common for fine and coarse aggregate stockpiles, timber framing, masonry units, and earthworks. In batch plants, aggregate moisture is measured daily or per shift to maintain target slump and water–cement ratio. In soil compaction, moisture content guides whether to aerate, mix, or add water.
Use direct masses when you can weigh the sample itself. Use the container method when the sample must stay in a tin or pan for handling and oven transfer. The calculator supports both approaches and automatically computes sample wet and dry masses from container readings, reducing transcription mistakes during busy testing.
Oven‑dry basis expresses water relative to dry solids, making it convenient for correcting batch water because the dry mass drives absorption behavior. Wet basis expresses water relative to total wet mass, which some inspectors prefer for quick communication. This tool shows both, so teams can align on the same basis in reports.
Aggregates absorb a portion of water into pores, while the remainder is free on the surface and affects the effective mixing water. Enter absorption (%) and a planned batch wet mass to estimate dry batch mass, free moisture, and the water adjustment needed. A positive adjustment means add water; negative means reduce added water.
Moisture varies widely by material and weather. Stockpiled sand can swing several percentage points after rain, while coarse aggregate often changes less but still matters at scale. Timber moisture depends on storage and target use; interior finish work typically demands tighter control than rough framing. Always follow your project specifications for acceptance limits.
Document sample ID, method, units, and drying notes so results remain auditable. Pair moisture values with date, location, and stockpile or member designation. Use the CSV for spreadsheets and the PDF for field records. Consistent moisture tracking reduces rework, supports stronger pours, and improves schedule reliability across teams.
1) Which basis should I report?
Use oven-dry basis for batch correction and technical logs. Use wet basis when your inspection reports require it. This calculator shows both so you can match your specification quickly.
2) What does constant mass mean?
Dry, cool, and reweigh the sample until repeat weights change only slightly. That stable value is the dry mass used for calculations, reducing error from incomplete drying.
3) Why is wet mass sometimes less than dry mass?
It usually indicates a weighing or entry mistake, or the container readings were mixed up. Recheck tare mass, then confirm wet-plus-container and dry-plus-container values.
4) How does moisture affect concrete strength?
If wet aggregate adds unaccounted water, the effective water–cement ratio increases, which can reduce strength and durability. Correcting batch water using measured moisture helps maintain consistent performance.
5) What is absorption and why does it matter?
Absorption is the water held within aggregate pores. It does not behave like free surface water. Comparing moisture to absorption helps estimate free moisture and the water adjustment for your mix.
6) Can I use pounds or kilograms?
Yes. Select your unit and keep every mass input in that same unit. The percentage moisture is unitless, while water mass and adjustment are reported in your chosen unit.
7) Why include sample ID and notes?
They improve traceability. IDs link results to stockpiles, locations, or members. Notes capture drying conditions, making your CSV/PDF reports easier to defend during reviews.
Accurate moisture checks protect quality, cost, and schedules daily.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.