Moisture Tracking ToolDrying Rate and Completion Tracker
Track the moisture content of wood over time during drying. Calculate drying rate, estimate days to target, monitor for stalling, and verify oven-dry moisture content from sample weights.
Why this calculation matters
Readings tell you whether stock is actually reaching target, or whether only the surface has dried while the core is still wet.
Moisture Tracking Tool
Drying Rate and Completion Tracker
Weigh the sample board now.
After drying at 103°C to constant weight.
MC at last check. Leave matching current if first reading.
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About Moisture Tracking Tool
The oven-dry sample method is the most accurate way to measure wood moisture content - far more reliable than pin meters for green and wet wood. By weighing a sample board over time, you can track the drying curve, calculate the daily drying rate, predict when the target MC will be reached, and catch a stalled or case-hardened load before it becomes a problem. Think of it as a wood moisture log for your stack — record readings over the weeks and watch air drying progress toward target.
Where Is This Used?
Formulas Used
MC% = (Wet weight - Oven-dry weight) / Oven-dry weight x 100Drying rate = (Previous MC - Current MC) / Days elapsedDays to target = (Current MC - Target MC) / Drying rateProgress % = (Start - Current) / (Start - Target) x 100Stall: drying rate near zero while MC still above targetHow the calculation works
Moisture content is expressed against the dry mass of the wood, not the wet mass, which is why it can exceed 100% in green timber. The projection assumes drying continues at the rate just measured.
Show the formula
Moisture content = (wet mass - oven-dry mass) / oven-dry mass x 100, the oven-dry basis of ASTM D4442. Drying rate = (previous MC - current MC) / days elapsed. Days to target = (current MC - target) / rate.Drying is closer to exponential than linear, so the projection over-reads late in a run as the rate falls. Meter readings need species and temperature correction; this uses the mass method.
References and what each one provides
- ASTM D4442ASTM InternationalThe oven-dry mass method for direct moisture content determination.
- USDA Wood Handbook (FPL GTR-190)USDA Forest Products LaboratoryPublished density, moisture relationships, shrinkage coefficients and mechanical properties for a wide range of species. The reference dataset behind most wood-property figures on this site.
Unverified values are marked as such rather than presented as sourced.
Limitations of this calculation
Records the readings entered. It does not account for meter calibration, species correction factors, temperature correction, depth of measurement, or the difference between surface and core moisture content.
Do not use this for Acceptance testing, dispute evidence, or contractual moisture certification. Those need a calibrated meter and a documented method.
Figures are engineering estimates from the inputs and assumptions shown. Verify against the actual material and, where the result affects structure or safety, against a qualified professional.
- ASTM D4442 oven-dry method: MC = (wet − ovendry) ÷ ovendry × 100
Formula checked against the sources above by an automated regression test (tests/verify-phase2.js) that derives each expected value independently of this page. Last reviewed .
How to use this tool
- Enter your wood and climate details below, then press Calculate.
- Fill in current sample weight, oven-dry weight, previous mc reading, days since last reading.
- Press Calculate.
Worked example
Common mistakes to avoid
- Measuring only the surface with pin meters. Drive pins deep or use a hammer probe for core readings.
- Measuring right after rain or washing. Surface moisture fools the meter for days.
- Tracking one board per stack. Moisture varies across a pack; sample several boards including the middle.
Frequently Asked Questions
Wood species data
Density, hardness and movement for 60 timbers