Free compost calculator. Find exactly how much compost you need in cubic feet, cubic yards, and bags for raised beds, gardens, and lawns.
Add prices to compare bagged vs. bulk compost.
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Whether you're building a new garden bed, top-dressing an existing garden, or improving your lawn, knowing the right amount of compost is essential. Our calculator helps you determine exactly how much compost to buy, whether in bags or bulk, saving you money and multiple trips to the garden center.
Compost is sold by volume — in dry quarts, cubic feet, or cubic yards. Bagged compost typically comes in 1, 1.5, and 2 cubic-foot bags (about 26, 40, and 51 US dry quarts), while bulk compost is sold by the cubic yard (27 cubic feet). The amount you need is simply your area multiplied by the application depth recommended for your project, from a light lawn top-dressing to a full raised-bed fill.
Volume Formula
Apply 2-4 inches of compost and work it into the top 6-8 inches of soil before planting.
Mix compost with topsoil at a 30-50% ratio when filling new raised beds for optimal growing conditions.
Top-dress existing gardens with 1-2 inches of compost each season to replenish nutrients.
Apply ¼ to ½ inch of fine compost over lawns and rake in to improve soil structure and grass health.
Buying the right amount means no wasted compost and no extra trips to the store. Bulk purchasing can save 30-50% over bags.
Too little compost won't provide enough benefit. Too much can smother plants or waste resources.
Know delivery requirements and costs upfront for better budgeting and scheduling.
Using the right amount supports soil health without excess that could lead to nutrient runoff.
At a 2-inch depth, 10 square feet needs about 1.7 cubic feet of compost; a 1-inch top-dressing needs roughly 0.8 cubic feet per 10 square feet. Multiply your area by the depth (in feet) to get cubic feet.
For projects under about 1 cubic yard, bags are convenient. For larger jobs, bulk delivery is usually 30–50% cheaper per cubic foot. One cubic yard (27 cubic feet) is roughly 17–18 of the common 1.5-cubic-foot (40 dry-quart) bags.
New garden beds: 2–4 inches worked into the soil. Existing gardens: 1–2 inches as a top-dressing. Lawns: ¼–½ inch of screened compost. Raised beds: 4–6 inches mixed with soil. These ranges follow university-extension guidance.
Finished compost weighs roughly 600–800 pounds per cubic yard depending on moisture, so this calculator estimates about 700 pounds per cubic yard. A half-ton pickup safely holds 1–2 cubic yards.
Yes. More than about 25–30% compost by soil volume can cause nutrient imbalances, especially excess phosphorus. Stick to the recommended depths and soil-test periodically.