Compost Calculator for Garden Beds
A garden bed takes 2–3 inches of compost worked into the top six inches of soil, which is about one cubic yard per 100 square feet.
Work out what you need
Measure the area, set the depth, and this converts it to cubic yards, what it weighs on the truck, how many bags that replaces, and roughly what it should cost delivered.
Weight is quoted as a band because moisture moves it more than grade does — compost after heavy rain runs to about 140% of its dry weight. The delivered range starts from a published $25–55 per cubic yard and is scaled by how your region's material prices compare with the national average, so treat it as a sanity check and not a quote.
Get a real price from yards near youNot a garden bed? The compost guide covers every other job.
Why 2–3 inches for a garden bed
Two to three inches worked in is a soil amendment, not a mulch layer. The point is what it does to the structure underneath, not what it looks like on top.
What goes wrong
Compost keeps shrinking after you spread it. A bed that looked right in spring sits an inch lower by autumn, which is normal and not a short load.
More than about three inches worked in and you get a bed that holds too much water and slumps as the organic matter finishes breaking down.
Compost by the numbers
| Weight per cubic yard | 1,000–1,600 lb dry |
|---|---|
| Tons per cubic yard | about 0.7 |
| Bags in a cubic yard | 27 × 1 cu ft bags |
| Half-ton pickup, one trip | about 0.75 cubic yards |
| Usually priced by the | cubic yard |
| Typical delivered price | $25–55 per cubic yard |
Finished compost runs 1,000–1,600 lb per yard — heavier than mulch, lighter than soil. Fresh or hot compost weighs more and smells like it.