Compost Calculator

Estimate how much compost you need for garden beds, raised beds, lawns, top dressing, soil amendment, and planting areas. Calculate compost volume, cubic feet, cubic yards, bags needed, bagged compost cost, bulk compost cost, and compost coverage.

Calculate Compost

Compost Volume = Area × Compost Depth. Convert compost depth from inches to feet before calculating volume.
Your result will appear here.

How the compost calculator works

Rectangular mode:
The calculator multiplies length, width, and compost depth to estimate compost volume.

Round mode:
The calculator uses diameter to estimate circular area, then multiplies by compost depth.

Known area mode:
The calculator uses your entered square footage and compost depth to estimate total compost needed.

Raised bed mix mode:
The calculator estimates compost as a percentage of the total raised bed or garden soil mix.

Why use a compost calculator?

A compost calculator helps estimate how much compost to buy before improving soil, filling beds, top dressing lawns, or preparing vegetable gardens.

It can help compare bagged compost and bulk compost, estimate total cost, and plan the right amount of compost for garden beds, lawns, raised beds, flowers, trees, shrubs, and planting areas.

What your result means

Your result shows estimated compost volume in cubic feet and cubic yards, bags needed, estimated bagged compost cost, estimated bulk compost cost, coverage area, compost depth, extra material allowance, and compost mix amount when using the raised bed mix option.

Compost formulas

Frequently asked questions

How do I calculate how much compost I need?

Multiply the area by the compost depth in feet. If your compost depth is in inches, divide it by 12 first. Then divide cubic feet by 27 to convert to cubic yards.

How much compost should I add to a garden bed?

A common compost layer for garden beds is about 1 to 2 inches. Heavy soil improvement may use more, while light seasonal refreshing may use less.

How much compost should I use for lawn top dressing?

Lawn top dressing often uses a thin layer, commonly around 1/4 to 1/2 inch. Thicker layers may smother grass if spread too heavily.

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

One cubic yard equals 27 cubic feet. Bagged compost is often sold in cubic feet, while bulk compost is usually sold by the cubic yard.

Is this compost calculator exact?

No. This is an estimate. Actual compost needs can vary based on bed shape, slope, soil condition, settling, compaction, moisture, and spreading depth.