Compost calculator
Measure the lawn or garden bed, pick a depth, and see how much compost to order in bulk or how many bags to buy.
Estimates round up. Check product labels and supplier figures before ordering.
How much compost to spread
| Use | Depth | 1 cu yd covers |
|---|---|---|
| Top-dressing a lawn | 1/4 in | about 1,300 sq ft |
| Top-dressing a thin lawn | 1/2 in | about 650 sq ft |
| Amending an existing bed | 1 in | 324 sq ft |
| Preparing a new bed | 2 in | 162 sq ft |
| Heavy amendment of poor soil | 3 in | 108 sq ft |
How it's calculated
Compost is sold by volume, so the calculator multiplies your area by the depth, converts inches to feet, and divides by 27 to get cubic yards.
Cubic feet = area (sq ft) x depth (in) / 12
Cubic yards = cubic feet / 27
Bags = cubic feet / bag size (cu ft)
Example: a 5,000 sq ft lawn top-dressed 1/4 inch deep needs about 104 cubic feet, which is about 3.86 cubic yards. A 200 sq ft vegetable bed with 2 inches of compost needs about 33 cubic feet, or 1.23 cubic yards, or 45 bags of 0.75 cubic feet.
Extension guides commonly suggest about 1/4 inch for a yearly lawn top-dressing, raked into the turf after aerating. For beds, 1 to 3 inches is typical, mixed into the top several inches of soil before planting. Thicker layers on a lawn can smother the grass. The extra field adds 5% for uneven spreading.
What you'll need
- Bagged compost
- Compost spreader
- Lawn aerator rental
- Garden rake
Common questions
How much compost do I need to top-dress a lawn?
About 1/4 inch, which works out to roughly 0.77 cubic yards per 1,000 sq ft. Going much past 1/2 inch can smother the grass.
How many bags of compost are in a yard?
A cubic yard is 27 cubic feet, so it equals 27 bags of 1 cubic foot or 36 bags of 0.75 cubic feet.
How much compost should I add to a garden bed?
Spread 1 to 3 inches and mix it into the top 4 to 8 inches of soil. Use the higher end for new beds or heavy clay.
When is the best time to spread compost?
For lawns, early fall or spring, ideally right after core aeration. For beds, a few weeks before planting or in fall after cleanup.