Landscaping
Landscaping Compost Calculator
Work out compost quantity for soil improvement or bed filling.
Result
Top dressing a lawn uses a quarter to a half inch; any more smothers the grass. Amending a bed before planting uses two to three inches dug in. Those are very different rates and using the bed rate on a lawn kills it.
Get a Free Business AuditWhat moves the number
- Whether compost is being incorporated as an amendment or used as a fill.
- Incorporation depth, since amendment is mixed into existing soil rather than layered on.
- Decomposition, which reduces volume over time.
Where this one goes wrong
Using compost as the entire growing medium. It is an amendment rather than a soil. Used alone it decomposes, slumps, and can hold too much water, and the planting suffers in the second season rather than the first.
Questions
About this calculator
How much compost should be incorporated?
A proportion of the soil volume being improved rather than a layer thickness. It is mixed in, so the calculation is about the ratio in the rooting zone.
Is compost a substitute for topsoil?
No. It has no mineral structure, it decomposes and it slumps. It improves soil, it does not replace it.
Does compost quality vary?
Considerably, including in maturity and contamination. Immature compost can harm planting, so source matters more than price on this material.
The formula
cubic yards = area x (depth / 12) / 27
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How to use this calculator
- Length (ft) (ft). Enter your own figure; the page starts at 40 ft.
- Width (ft) (ft). Enter your own figure; the page starts at 25 ft.
- Application depth (inches) (in). Enter your own figure; the page starts at 0.5 in.
- Waste / compaction allowance (%). Enter your own figure; the page starts at 5%.
- Cost per cubic yard ($). Enter your own figure; the page starts at $45.
The result updates as you type, so you can try a figure, see what it does to cubic yards needed, and change it back. Nothing you enter is sent anywhere or saved.
A worked example
These are the figures the calculator opens with. Every number in the results column below is produced by the same calculation the page runs, so you can follow it through before putting your own figures in.
What goes in
| Input | Value |
|---|---|
| Length (ft) | 40 ft |
| Width (ft) | 25 ft |
| Application depth (inches) | 0.5 in |
| Waste / compaction allowance | 5% |
| Cost per cubic yard | $45 |
What comes out
| Result | Value |
|---|---|
| Cubic yards needed main result | 1.6 |
| Cubic feet | 43.8 |
| Approximate tons | 1.3 |
| Estimated cost | $72.92 |
You need about 1.6 cubic yards (1.3 tons), costing roughly $72.92 delivered.
How sensitive the answer is
Holding everything else steady and changing only cost per cubic yard, this is what happens to cubic yards needed. It is worth knowing which of your inputs the answer actually hinges on, and which barely move it.
| Cost per cubic yard ($) | Cubic yards needed |
|---|---|
| $23 | 1.6 |
| $34 | 1.6 |
| $45 example above | 1.6 |
| $68 | 1.6 |
| $90 | 1.6 |
Every other input is held at the example value while this one changes, which is not how a real job behaves. Treat it as a guide to which number matters most, not as five separate quotes.
What each figure means
- Length (ft) (ft)
- Measured in ft, starting at 40 ft.
- Width (ft) (ft)
- Measured in ft, starting at 25 ft.
- Application depth (inches) (in)
- Measured in in, starting at 0.5 in.
- Waste / compaction allowance (%)
- A percentage, between 0 and 60, starting at 5%.
- Cost per cubic yard ($)
- A money amount, starting at $45.
What the results tell you
| Result | What it is |
|---|---|
| Cubic yards needed | The headline result. A decimal figure. |
| Cubic feet | A decimal figure. |
| Approximate tons | A decimal figure. |
| Estimated cost | A money figure. |
Seasonality is not in this
Coverage and material figures assume the area you enter. Slope, access for machinery, existing growth and the time of year all affect both quantity and labour, and none of them appear in a calculation like this.
Keep going
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