Free compost calculator to determine exactly how much compost you need. Get volume in cubic feet, cubic yards, and bags for raised beds, gardens, and lawns.
New Garden Bed
Creating a new garden bed from scratch. Mix compost into the top 6-8 inches of soil.
Recommended depth: 2-4 inches
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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—typically in quarts, cubic feet, or cubic yards. A standard bag contains about 40 quarts (1 cubic foot). For larger projects, bulk compost is sold by the cubic yard (27 cubic feet). The amount you need depends on your area size and the recommended application depth for your specific gardening purpose.
Volume Formula
Volume = Length × Width × DepthBuying 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.
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.
For new gardens, plan on 1-1.3 cubic feet per 10 square feet at a 2-inch depth. For top-dressing, you'll need about 0.5-1 cubic foot per 10 square feet at a 1-inch depth.
For projects under 2 cubic yards, bags are convenient. For larger projects, bulk delivery is more economical—often 30-50% cheaper per cubic foot. One cubic yard equals about 27 standard 40-quart bags.
New gardens: 2-4 inches mixed into soil. Existing gardens: 1-2 inches as mulch. Lawns: ¼-½ inch screened compost. Raised beds: 4-6 inches mixed with soil.
Finished compost weighs approximately 600-800 pounds per cubic yard, depending on moisture content. A pickup truck typically holds 1-2 cubic yards safely.
Yes. Excessive compost (over 25-30% of soil volume) can cause nutrient imbalances, particularly excess phosphorus. Follow recommended depths and soil test periodically.