Soil Amendment Mix Calculator
The mix calculator converts a target volume and ingredient percentages into litres for each component. The entered percentages must total 100% within a small rounding tolerance.
How to use this calculator
- Enter total volume and component percentages that sum to 100%.
- Check that all inputs use the same units, period and population scope.
- Change one assumption at a time when comparing scenarios.
Formula used by soil amendment mix calculator calculator
Component volume = total mix volume × component percentage ÷ 100.
- Component volume = total mix volume × component percentage ÷ 100.
- Percentages are by volume. Material density, moisture and suitability differ; recipe proportions should follow the plant, soil and product needs.
- The tool validates inputs and rounds displayed figures for readability; it does not validate assumptions against external records.
Worked examples
Worked example
For a 200 L blend of 40% compost, 40% topsoil, 15% sand and 5% other amendment, each volume follows its share.
Compost 80 L; topsoil 80 L; sand 30 L; other amendment 10 L.
The component volumes add to 200 litres.
Understanding the result
The mix calculator converts a target volume and ingredient percentages into litres for each component. The entered percentages must total 100% within a small rounding tolerance.
Percentages are by volume. Material density, moisture and suitability differ; recipe proportions should follow the plant, soil and product needs.
Important notes
Percentages are by volume. Material density, moisture and suitability differ; recipe proportions should follow the plant, soil and product needs.
Treat the result as an estimate from the entered assumptions. For commercial, statistical, engineering or health-related decisions, verify relevant specifications and professional guidance.
Frequently asked questions
Can percentages sum to 99.9%?
Small rounding differences up to 0.1 percentage point are accepted; larger gaps are rejected.
Is every mix appropriate for potting plants?
No. Use an appropriate horticultural recipe for the plant and container.
How should I interpret this result?
Percentages are by volume. Material density, moisture and suitability differ; recipe proportions should follow the plant, soil and product needs.
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Related explanations
Learn the method behind the number or compare the terminology before using the calculator.
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This page provides a calculation tool plus explanatory information so you can understand what the result means and when the underlying method may not fit your situation.