Compost Calculator

To find how much compost you need, multiply the area by the depth and divide by 27 for cubic yards. To amend a bed, 1 to 3 inches worked into the soil is typical; to top-dress a lawn, a quarter to half an inch is plenty.

Length (feet)Width (feet)

Depth (inches)Bag sizeWaste / overage (%)

0.25-0.5 in to top-dress a lawn, 1-3 in to amend a bed before digging in.

Add prices to estimate cost (optional)

Price per bag ($)Price per cubic yard ($)

Enter your measurements above to see how much compost you need.

How much compost to add

For a new or tired planting bed, spread 1 to 3 inches of compost and dig or till it into the top several inches of soil. For an established lawn, a thin quarter to half inch top-dressing is enough.

Measure the bed in feet, set the depth, and the calculator returns cubic yards and the number of bags for the size you buy.

Bags or bulk?

Bagged compost suits small beds and containers. For a large garden or lawn top-dressing, bulk compost by the cubic yard is far cheaper.

One cubic yard covers about 324 square feet at a 1 inch depth, or about 108 square feet at 3 inches.

Compost coverage chart

DepthPer 1 cu ft bagPer cubic yard

1 in12 sq ft324 sq ft

2 in6 sq ft162 sq ft

3 in4 sq ft108 sq ft

One cubic yard = 27 cubic feet. Coverage = volume / depth.

Frequently asked questions

How much compost do I need to amend soil?

Spread 1 to 3 inches over the bed and work it into the top 6 to 8 inches of soil. For a cubic-yard estimate, multiply area by depth in feet and divide by 27.

How much compost to top-dress a lawn?

A quarter to half inch is plenty. One cubic yard top-dresses roughly 650 to 1,300 square feet at that thickness.

How many bags of compost in a cubic yard?

With 1 cu ft bags it is 27 per cubic yard; with 1.5 cu ft bags it is 18; with 2 cu ft bags it is about 14.

Related calculators

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Helpful guides

How Deep Should Mulch Be?2-3 in to refresh, 3-4 in for new beds - and why more is not better.How Much Grass Seed Per Square Foot?~5 lb/1,000 sq ft new, ~3 lb to overseed - and why type matters.Mulch Types ComparedHardwood, bark, pine straw, rubber, stone - which to use where.Topsoil vs Garden Soil vs CompostWhat each one is for, and how to combine them.

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