Compost Calculator

Calculate how much compost you need for garden beds, raised beds, lawns, topdressing, planting areas, and soil amendment projects. Estimate cubic feet, cubic yards, bags, weight, coverage, and total compost cost.

Calculate Compost Needs

Compost Volume = Area × Compost Depth.
Your result will appear here.

How the compost calculator works

Compost from area:
The calculator multiplies project area by compost depth to estimate the compost volume needed.

Raised bed / rectangle:
Enter length, width, and compost depth to estimate compost for a bed, planter, or rectangular area.

Known volume:
Enter an existing compost volume to convert it into cubic feet, cubic yards, gallons, liters, bags, weight, and cost.

Soil mix compost amount:
Enter total soil mix volume and desired compost percentage to estimate the compost portion of the mix.

Why use a compost calculator?

A compost calculator helps estimate how much compost to buy before spreading, filling beds, amending soil, or mixing potting soil.

It can be useful for raised beds, vegetable gardens, flower beds, lawns, container gardening, tree planting, soil improvement, and bulk compost delivery planning.

What your result means

Your result shows compost volume before and after extra allowance, cubic feet, cubic yards, cubic meters, gallons, liters, bags needed, estimated weight, bag cost, bulk compost cost, and total cost. These are planning estimates based on your area, depth, bag size, density, and prices.

Compost formulas

Frequently asked questions

How do you calculate how much compost you need?

Multiply the project area by the compost depth using the same unit. Convert the result to cubic feet, cubic yards, or bags as needed.

How much compost should I add to a garden bed?

For many garden beds, a 1 to 2 inch layer is common for yearly amendment, while new beds may use a deeper layer depending on soil condition.

How many cubic feet are in a cubic yard of compost?

One cubic yard equals 27 cubic feet.

Should I buy bags or bulk compost?

Bags can be easier for small projects, while bulk compost is often better for larger beds, lawns, or landscaping projects.