Exact material estimates for every home & DIY project.

Compost Calculator

A compost calculator works out how much compost you need — in cubic yards and bags — to top-dress a lawn or amend a garden bed, from the area and the depth you want to apply.

Your measurements

Result
0

A thin layer goes a long way on lawns; beds take more worked into the soil. Set the depth and it converts to bulk yards or bags.

How it is calculated

Volume = area × depth, in cubic yards (÷ 27 cubic feet); bag count assumes 1.5 ft³ bags. Compost is light, around half a ton per cubic yard. Apply thin on lawns and deeper in beds.

Steps

  1. Enter the area, or length and width.
  2. Set the depth — 1/4-1/2 in to top-dress a lawn, 1-3 in to amend a bed.
  3. Read the cubic yards or the bag count.
  4. Work it into the top few inches of bed soil.
  5. Re-apply each season as it breaks down.

Worked example

A 200 sq ft bed at 2 in deep needs about 1.23 cubic yards of compost — roughly 22 bags of 1.5 ft³.

Common questions

How much compost do I need?
Area × depth gives the volume. Use 1/4-1/2 in on lawns and 1-3 in in beds; the calculator converts to yards and bags.
How deep should compost be?
A light 1/4-1/2 in to top-dress a lawn, or 1-3 in worked into a planting bed.
How many bags of compost in a yard?
About 18 bags of 1.5 ft³ make a cubic yard (27 cubic feet).
Compost or topsoil?
Topsoil is the bulk growing medium; compost is the organic amendment you mix into it or spread on top to feed the soil.

Related calculators