VOLUME
Cubic yard calculator
One cubic yard is 27 cubic feet — a cube 3 ft × 3 ft × 3 ft. That is a definition, not a measurement, so it needs no source and never varies. Everything else on this page is that one fact combined with your area and depth.
Square feet and inches to cubic yards
cubic yards = square feet × depth in inches ÷ 324
The 324 is where the two conversions meet: 27 cubic feet in a cubic yard, times 12 inches in a foot. It is the same number whether you are ordering mulch, topsoil, compost, gravel, playground surfacing or potting mix — and it is the reason one cubic yard covers 324 sq ft at one inch deep and 108 sq ft at three.
Worked examples, checked
| Area | Depth | Calculation | Cubic yards |
|---|---|---|---|
| 100 sq ft | 3 in | 100 × 3 ÷ 324 | 0.93 |
| 324 sq ft | 1 in | 324 × 1 ÷ 324 | 1.00 |
| 200 sq ft | 2 in | 200 × 2 ÷ 324 | 1.23 |
| 1,000 sq ft | 4 in | 1,000 × 4 ÷ 324 | 12.35 |
How much does one cubic yard cover?
Divide 324 by the depth in inches:
- 1 inch: 324 sq ft
- 2 inches: 162 sq ft
- 3 inches: 108 sq ft
- 4 inches: 81 sq ft
- 6 inches: 54 sq ft
- 12 inches: 27 sq ft
That table is the fastest sanity check there is on a bulk quote. An independent published version of it, from a university extension service rather than from us:
“One cubic yard of compost will cover about 108 square feet when applied to a depth of 3 inches; 216 square feet at a depth of 2 inches; or 324 square feet at a depth of 1 inch.”
NC State Extension, Organic Lawn Care, appendices, read 2026-09-21.
Their three figures are this page's 3-inch, 2-inch and 1-inch rows exactly, which is what you would expect: the arithmetic is arithmetic, whatever the material.
Square feet to cubic yards, written out as a calculator
The conversion on this page takes two inputs — area and depth — and it is worth stating plainly in the form a calculator would use:
input: square feet and depth in inches → output: cubic yards = square feet × depth ÷ 324
Three worked inputs, so you can check any figure you are handed:
- 50 sq ft at 3 in → 50 × 3 ÷ 324 = 0.46 cubic yards
- 500 sq ft at 2 in → 500 × 2 ÷ 324 = 3.09 cubic yards
- 2,000 sq ft at 6 in → 2,000 × 6 ÷ 324 = 37.04 cubic yards
If what you have is cubic feet rather than square feet and inches, divide by 27 — or run square feet × depth ÷ 12 ÷ 27, which lands in the same place. Check it on the first row: 50 × 3 ÷ 12 = 12.5 cubic feet, and 12.5 ÷ 27 = 0.46 cubic yards.
Going the other way
Given a volume and an area, the depth is inches = cubic yards × 324 ÷ square feet. This is the check to run when a supplier quotes you a number and you want to know what it actually means on the ground. A quote of 2 cubic yards over a 200 sq ft bed is 2 × 324 ÷ 200 = 3.24 inches — deeper than the 2 to 4 inch range most beds want, and worth questioning before it arrives.
Cubic feet, cubic yards and the units people mix up
cubic feet = cubic yards × 27cubic yards = cubic feet ÷ 27cubic feet = square feet × depth in inches ÷ 12- Bagged material:
bags = ceiling(cubic feet ÷ cubic feet per bag)
The one that causes real ordering errors is the third: square feet times inches is not cubic feet until you have divided by 12. A 200 sq ft bed at 2 inches is 400 square-foot-inches, which is 33.33 cubic feet — not 400.
Where this number is used on this site
Every bulk material calculator here runs on this conversion: mulch, topsoil, compost, gravel, pea gravel, landscape rock and playground surfacing. What changes between them is the depth each job calls for and the package each is sold in — not the arithmetic.
Source for the coverage figures quoted: NC State Extension, Organic Lawn Care: A Guide to Organic Lawn Maintenance and Pest Management, appendices, content.ces.ncsu.edu, read 2026-09-21. The 27-cubic-feet-per-cubic-yard relationship is a definition and is not sourced from a page.
Cite this dataset
The mulch coverage, bag-count and dated price tables from this site are archived as a citable dataset: Mulch coverage, bag-count and dated bulk price tables, version v1, published 20 September 2026, 9 files, creator ERTHK — DOI 10.5281/zenodo.22855990, record at zenodo.org/records/22855990.
Released under CC0 1.0 Universal (Creative Commons Zero v1.0 Universal): free to copy, modify and redistribute.
The source library that generates the tables, with its test suite, is at github.com/ERTHK/mulch-measure-calculator-kit, released under the MIT license.