Compost Moisture
Find a compost pile's moisture content from its weight.
About Compost Moisture
Moisture content is the water weight as a share of the wet weight, found by drying a sample and comparing the two weights. Compost microbes need about half moisture; too wet turns anaerobic and smelly while too dry stops the pile from heating.
Formula
Compost Moisture
Moisture% = (wet - dry) ÷ wet x 100
- wet weight
- Weight of a fresh, undried compost sample
Worked example
With the default values below, Compost Moisture returns Moisture Content of 30.0%. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Wet sample weightminimum 0 lbs
- 20 lbs
- Dry sample weightminimum 0 lbs
- 14 lbs
Results
- Moisture Content
- 30.0%
- Moisture Status
- Too dry - add water
- Water Weight
- 6.00 lbs
Step by step
- 1Values used
- 2Compost Moisture
- 3Moisture Content= 30.0
- 4Moisture Status= Too dry - add water
- 5Water Weight= 6.00 lbs
Assumptions and limits
- The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Compost Moisture calculated?
Moisture% = (wet - dry) ÷ wet x 100 Moisture content is the water weight as a share of the wet weight, found by drying a sample and comparing the two weights.
Why does Compost Moisture matter?
Compost microbes need about half moisture; too wet turns anaerobic and smelly while too dry stops the pile from heating.
What values do I need to enter?
This calculator takes 2 inputs: Wet sample weight, Dry sample weight. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.