Estimate compost volume for a garden bed or lawn, then convert it into cubic yards, cubic feet, liters, and bag counts. Adjust the suggested depth to match your soil and plan.
A planning depth—not a soil test or universal recommendation.
Check the package; bag sizes vary.
The garden and lawn presets use University of Minnesota Extension starting points: about 1/2 inch for vegetable and flower gardens, and 1/4 inch for lawns. These refer to non-manure compost. Soil test results, compost type, climate, and local advice can call for a different amount.
Compost adds nutrients as well as organic matter. Nutrient levels vary by source, and repeated heavy applications can build up phosphorus and potassium. A soil test helps decide whether more compost is useful; treat composted manure as a fertilizer source.
The calculator multiplies the area you enter by the application depth, converts that volume to cubic yards or cubic meters, and divides by the package size you provide. Bag counts round up to a whole package; the bulk volume remains unrounded for ordering.
For U.S. units: cubic yards = square feet × depth in inches ÷ 324. For metric: cubic meters = square meters × depth in centimeters ÷ 100. For irregular beds, add their areas together and enter the total area instead of trying to turn them into a rectangle.
Planning example: a 5 × 10 ft garden bed with a 2 in layer is 50 × 2 ÷ 324 = 0.31 cubic yards, or around 8.4 bags at 1 cubic foot each. The 2-inch depth is an example calculation, not a recommended annual application.
Measure the bed area and choose a depth based on your soil and gardening plan. As one example, University of Minnesota Extension recommends about 1/2 inch of non-manure compost for vegetable and flower gardens when soil testing indicates compost is appropriate. The amount is not a universal prescription; soil test results and compost nutrient content matter.
This calculator starts with a 1/4-inch layer, matching University of Minnesota Extension guidance for lawn top-dressing with non-manure compost. Use a thin, even layer that does not smother the grass, and check local lawn or extension guidance for your conditions.
For U.S. measurements, multiply the area in square feet by the depth in inches, then divide by 324 to get cubic yards. For example, 50 square feet at 2 inches is 50 × 2 ÷ 324 = about 0.31 cubic yards. The calculator also converts the result to cubic feet, liters, and bags.
It depends on the bag size. A cubic yard is 27 cubic feet, so it takes 27 one-cubic-foot bags or 18 bags that each hold 1.5 cubic feet. Enter the volume printed on your bag to get a rounded-up count.
This tool calculates volume, not a planting-medium recipe. Compost varies in nutrient and salt content, and repeated or heavy applications can build up nutrients such as phosphorus. For a new bed, use a suitable soil-and-compost blend based on local extension guidance and your soil needs; don’t treat the whole bed volume as a compost recommendation.
Not automatically. Manure-based compost can contribute substantially different nutrients than food-scrap or yard-waste compost. University of Minnesota Extension advises treating composted manure as a fertilizer source and using soil tests to guide applications.
Application guidance: University of Minnesota Extension on how much compost to apply. It recommends soil testing and about an inch or less for garden beds each year; its soil testing guidance gives the specific 1/2-inch garden and 1/4-inch lawn starting points used here for non-manure compost.
For a visual explanation of measuring area, choosing depth, and converting cubic yards to bags, see Marion Owen’s compost, mulch, and topsoil calculation walkthrough. The video’s application examples differ from the Extension presets above, which is why the calculator lets you change the depth.
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