Calculator
Compost Calculator
Use a thin layer (about 1 inch) for an annual top-dress. Use a thicker share of the mix when you are filling a new raised bed. Compost quality matters more than hitting an exact cubic footage.
Your result
Estimated bags
2bags2 cu ft each
- Cubic feet
- 2.67 cu ft
- Cubic yards
- 0.099 cu yd
- Estimated bags
- 22 cu ft bags, rounded up
How this calculation works
Volume (cu ft) = length (ft) × width (ft) × (depth in inches ÷ 12). Bags = cubic feet ÷ bag size, rounded up.
Example: 4×8 bed, 1-inch top-dress
4 × 8 × (1 ÷ 12) = 2.67 cubic feet. With 1 cu ft bags, that is 3 bags. If compost is one-third of a 12-inch soil mix in the same bed, you would need about 10.7 cubic feet of compost.
Frequently asked questions
How much compost should I add each year?
A ½- to 1-inch top-dress in spring is a common home-garden practice. If plants were weak last season or soil looks tired, a full inch is reasonable. Excess compost can throw off nutrient balance, especially with high-nitrogen feeds.
Is all bagged compost the same?
No. Some bags are mostly bark fines. Look for a dark, earthy mix that lists feedstocks such as yard waste, food scraps, or manure, and avoid bags that smell sour or look like wood chips.