How to use the garden compost calculator
- Enter the length, width and height of the pile or bin.
- Enter the bag size if you are buying bagged compost. The default 1 cubic foot is editable; many bags are 1 or 2 cubic feet.
Raised-bed and topsoil fills stay on the topsoil calculator. Surface dressings are on the mulch calculator. Nutrient rates are on the fertilizer calculator.
Pile volume
Volume (cu ft) = length × width × height, in feet. Bags = volume ÷ bag size, rounded up. A cubic yard is 27 cubic feet.
A worked example: 4×4×3 ft pile
A 4 × 4 × 3 ft pile is 48 cubic feet, or 1.78 cubic yards. That is 48 bags of 1 cubic foot, or 24 bags of 2 cubic feet.
Sources & assumptions
How this calculator gets its numbers. Full method: our methodology.
- Pile or bin volume = length × width × height, in feet. Bags = volume ÷ bag size, rounded up. Default bag size 1 cu ft is an editable starting point.
- This is garden compost only, not a topsoil or raised-bed fill (those stay on the topsoil calculator).
Sources
- NIST, Handbook 44 (2026), Appendix C — General Tables of Units of Measurement. Units of Volume: 27 cubic feet = 1 cubic yard; the calculator reports both.
Last reviewed . The bag size printed on the product you buy wins.
Frequently asked questions
How much compost is in a 4×4×3 ft pile?
48 cubic feet, about 1.78 cubic yards. That is 24 bags of 2 cubic feet.
Does this replace the topsoil calculator?
No. Raised-bed and topsoil fills stay on the topsoil calculator. This page is garden compost pile or bin volume.
What bag size should I enter?
Read the bag. The default 1 cubic foot is a starting point; 2 cubic foot bags are also common.
Does this tell me how much compost to spread on a bed?
Not as a topsoil replacement. For a bed fill, use the topsoil calculator. This page sizes a pile or the bags to fill a bin.