Compost calculator: how much compost do I need?
0.93 cubic yards
25 cubic feet · for 10 × 10 ft at 3 in
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Enter it the way you measured it: 4.5, 4 1/2,
3/8 or 10' 6".
0.93 cubic yards
25 cubic feet
Source: Oregon State University Extension, EM 9308, How to use compost in gardens and landscapes, compost depth for each use, read October 14, 2026. Read the source
A 10 by 10 ft garden bed at 3 inches deep needs 0.93 cubic yards of compost, which is 25 cubic feet. Oregon State University Extension gives 3 to 4 inches for a new vegetable bed.
A worked example
A 52 by 37 ft lawn topdressed 1/2 inch deep after core aeration needs 2.97 cubic yards. 1,924 square feet at half an inch is 80.2 cubic feet, the top of the 1/4 to 1/2 inch range Oregon State Extension gives for topdressing an existing lawn.
How deep should compost be?
Oregon State University Extension gives these depths of compost to add. New vegetable beds: 3 to 4 inches. Existing vegetable beds: 1/4 to 1 inch a year. Landscape areas before planting: 3 to 4 inches, mixed 6 to 8 inches into the soil. Raised beds: 2 to 3 inches over the broken-up ground before filling. Enter the depth for your use above.
How much compost do I need for a lawn?
For a new lawn, Oregon State Extension says to add 1 to 2 inches of compost as you prepare the soil and till it in: 1,000 square feet at 1 inch is 3.09 cubic yards. To topdress an existing lawn, it gives 1/4 to 1/2 inch spread after core aeration: 1,000 square feet at 1/4 inch is 0.78 cubic yards. Enter your lawn and the depth above.
What else it is called
Compost is sold in bulk by the cubic yard as compost, garden compost or soil amendment, and in bags of about 1 to 2 cubic feet. A 1 cubic foot bag covers 12 square feet 1 inch deep, so the cubic feet under the result is also the number of 1 cubic foot bags.
Common sizes
| Area | 0.5 in deep | 1 in deep | 2 in deep | 3 in deep | 4 in deep |
|---|---|---|---|---|---|
| 8 × 8 ft | 0.10 | 0.20 | 0.40 | 0.60 | 0.80 |
| 10 × 10 ft | 0.16 | 0.31 | 0.62 | 0.93 | 1.24 |
| 10 × 12 ft | 0.19 | 0.38 | 0.75 | 1.12 | 1.49 |
| 12 × 12 ft | 0.23 | 0.45 | 0.89 | 1.34 | 1.78 |
| 12 × 16 ft | 0.30 | 0.60 | 1.19 | 1.78 | 2.38 |
| 16 × 20 ft | 0.50 | 0.99 | 1.98 | 2.97 | 3.96 |
| 20 × 20 ft | 0.62 | 1.24 | 2.47 | 3.71 | 4.94 |
Cubic yards, rounded up to two decimals. Round up again to what your supplier will deliver.
Where the numbers come from
- Cubic yards are length times width times depth in feet, divided by 27. 1 cubic yard = 27 cubic feet, exact by definition.
- Depth for each use: Oregon State University Extension, EM 9308, How to use compost in gardens and landscapes. New vegetable beds 3 to 4 inches, existing beds 1/4 to 1 inch a year, landscape areas 3 to 4 inches, raised beds 2 to 3 inches, new lawns 1 to 2 inches, topdressing an existing lawn 1/4 to 1/2 inch. Read October 14, 2026. OSU Extension EM 9308
Bulk compost is ordered by the cubic yard. Enter the depth of compost you will spread, before it is mixed in or settles: the depths in the guide are amounts to add on top, not the final depth of the soil.
By Javier Miralles · Last updated . How this site is made.
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