One cubic yard spread uniformly covers 162 sq ft at 2 inches, 108 sq ft at 3 inches or 81 sq ft at 4 inches. The geometric formula is coverage (sq ft) = 324 / depth (in). It assumes the cubic yard and the selected layer depth describe the same material state. A loose delivered yard is not automatically a compacted installed yard.
Why the number is 324
One cubic yard is 27 cubic feet. One inch is 1/12 foot, so 27 / (depth / 12) = 324 / depth. The cited Texas AgriLife Extension handout gives the equivalent formula area × depth / 324 = cubic yards for soil, compost and mulch.1 Applying that dimensional geometry to gravel is our calculation, not a gravel density or depth recommendation from the handout.
Coverage of one cubic yard
No allowance, compaction conversion or order rounding. Depths are calculation scenarios, not specifications for paths, driveways, drainage or foundations.
| Selected layer depth | Geometric coverage (sq ft) |
|---|---|
| 0.5 in | 648 |
| 1 in | 324 |
| 1.5 in | 216 |
| 2 in | 162 |
| 3 in | 108 |
| 4 in | 81 |
| 6 in | 54 |
| 8 in | 40.5 |
| 12 in | 27 |
Volume required for common areas
Uniform rectangular layers. Installed or loose volume depends on which state the selected depth represents. Displayed values are rounded; calculations keep full precision.
| Area (sq ft) | At 2 in (cu yd) | At 3 in (cu yd) | At 4 in (cu yd) |
|---|---|---|---|
| 100 | 0.617284 | 0.925926 | 1.234568 |
| 144 | 0.888889 | 1.333333 | 1.777778 |
| 200 | 1.234568 | 1.851852 | 2.469136 |
| 400 | 2.469136 | 3.703704 | 4.938272 |
| 600 | 3.703704 | 5.555556 | 7.407407 |
| 1000 | 6.172840 | 9.259259 | 12.345679 |
A ton is not a cubic yard
Cu yd = US short tons / short tons per cu yd.
Coverage per US short ton = 324 / depth / short tons per cu yd. A US short ton is 2,000 lb; a metric tonne is a different unit. Get the actual supplier’s density for the selected product, moisture and volume state before converting.
American Rock Supply’s current calculator lists approximate examples of 1.50 short tons/cu yd for road base, 1.40 for several gravel products and 1.35 for river rock.2 These are that supplier’s calculator assumptions, not a guaranteed 1.35-1.40 range for all gravel. We use 1.40 only as a stated comparison input below. Confirm the matching density and volume state before relying on it.
| Selected depth | One cu yd (sq ft) | One short ton at example 1.40 t/cu yd (sq ft) |
|---|---|---|
| 1 in | 324 | 231.428571 |
| 2 in | 162 | 115.714286 |
| 3 in | 108 | 77.142857 |
| 4 in | 81 | 57.857143 |
| 6 in | 54 | 38.571429 |
Three checked examples
1. Cover 100 sq ft at 3 inches
Net volume = 100 × 3 / 324 = 0.925926 cu yd. At example 1.40 short tons/cu yd for that same state: 1.296296 short tons. With a separately chosen 10% quantity allowance: 1.018519 cu yd, or 1.425926 short tons under that same density assumption. The 10% allowance is an example, not a source recommendation.
2. Cover 400 sq ft at 2 inches
Net volume = 400 × 2 / 324 = 2.469136 cu yd. At the example density: 3.456790 short tons. If the supplier sells in 0.5-short-ton increments and no separate allowance applies, that rounds up to 3.5 short tons. The sales increment is hypothetical; check the actual supplier and quantity state.
3. What will 5 short tons cover at 3 inches?
At example 1.40 short tons/cu yd: 5 / 1.40 = 3.571429 cu yd. Area = (5 / 1.40) × 324 / 3 = 385.714286 sq ft. That is geometry before any handling loss or change in material state. Do not round the volume to 3.57 and then use it as an exact intermediate value.
Loose, compacted and added-depth quantities
If the supplier quotes loose cubic yards but your design specifies compacted thickness, calculate the installed volume and obtain a material-specific conversion to delivered loose quantity. Keep any separate handling allowance distinct. The coverage formula itself does not prove how much a material compacts, and a generic extra percentage does not solve a missing conversion.
For an existing layer, estimate the added thickness or separate low areas rather than ordering a full replacement depth by accident. Split irregular areas into non-overlapping regions and sum their volumes. If depth varies evenly across a rectangular region, an appropriate average depth can represent its volume; random dips need a measured takeoff rather than an assumed average.
Before ordering
- Confirm actual area and required added depth. The charts do not select a suitable gravel section.
- Label volumes as loose or compacted and verify any conversion.
- Use supplier density matched to the actual material and state if ordering by weight.
- Choose a separate allowance, then round to confirmed sales increments. Do not round intermediate volume or density calculations.
- Check delivery access, minimum quantities and fees separately. Coverage is not a truck payload calculation.
FAQ
How much does a yard cover at 2 inches?
Geometrically, 162 sq ft: 324 / 2. This assumes the yard and the 2-inch layer describe the same state, with no separate loss allowance.
How much does one ton cover?
It depends on density and depth. At the example 1.40 short tons/cu yd and 3-inch depth, 77.142857 sq ft per short ton, before any separate conversion or loss. This is not a universal gravel coverage figure.
Does this volume formula work for soil or mulch?
The dimensional formula is the same for a stated volume spread at a stated depth. Each material’s loose/settled state and weight conversion remain separate checks. The cited handout itself is about soil, compost and mulch.
Should I add 10% for compaction?
The examples use 10% only as a separate quantity scenario. Verify the actual material’s loose-to-compacted conversion rather than assuming that percentage represents compaction.
Related tools
Gravel calculator | Cubic-yard formula guide | Per-ton coverage guide
Sources
- Texas AgriLife Extension: How Much Compost, Soil or Mulch (area × depth / 324 dimensional formula; not gravel density or design)
- American Rock Supply: Gravel Calculator (supplier-specific approximate material density assumptions, not universal gravel values)