To work out how much gravel you need, multiply length × width × depth in feet, divide by 27 for cubic yards, then multiply by about 1.4 to get tons of pea gravel or #57 stone. A 20 × 10 ft area at 3 in deep takes 1.85 yd³, or about 2.6 tons. Order 5 to 10% extra for compaction.
You need three measurements: the length and width of the area in feet, and the depth you want in inches. Then:
That's exactly what our gravel calculator does, and the example above is its default. The third step is the one people skip, and it matters because of how gravel is sold. Landscape yards often price by the cubic yard. Quarries and many stone suppliers price by the ton. If you only know yards and the quote is in tons, you can't compare.
For odd shapes, split the area into rectangles and add them up. A circle is π × radius², so a 10 ft round fire-pit area is 3.1416 × 5 × 5 = 78.5 sq ft.
It depends on the stone. Denser rock weighs more per yard, and crushed stone with fines packs tighter than rounded gravel. These are the densities the calculator uses, and what they mean when a supplier quotes by the ton:
| Material | Tons per cubic yard | Cubic yards per ton | Cubic feet per ton |
|---|---|---|---|
| Pea gravel, #57 stone | 1.4 | 0.71 | 19.3 |
| Crushed stone | 1.5 | 0.67 | 18.0 |
| Sand, topsoil | 1.35 | 0.74 | 20.0 |
| Dense limestone | 1.7 | 0.59 | 15.9 |
These are typical bulk figures, not guarantees. Wet stone weighs more than dry, and one quarry's #57 won't weigh the same as another's. When you place the order, give the supplier both the yardage and the tonnage and ask which one they'll bill. That keeps the invoice close to your estimate.
Here's where depth takes over. A ton of pea gravel covers about 116 sq ft at 2 in but only 58 sq ft at 4 in. Double the depth, half the coverage.
| Depth | Sq ft per cubic yard | Pea gravel / #57 (per ton) | Crushed stone (per ton) | Dense limestone (per ton) |
|---|---|---|---|---|
| 1 in | 324 | 231 | 216 | 191 |
| 2 in | 162 | 116 | 108 | 95 |
| 3 in | 108 | 77 | 72 | 64 |
| 4 in | 81 | 58 | 54 | 48 |
| 6 in | 54 | 39 | 36 | 32 |
Use this table backwards when you've got a fixed budget. If you can afford 5 tons of crushed stone at 3 in, that's about 360 sq ft of coverage. Spread it thinner and you'll see soil through it in a season.
Depth depends on what the gravel has to do. Decorative gravel just needs to hide the ground. A driveway has to carry a two-ton car without rutting.
The same rule applies under concrete. Most slabs sit on about 4 in of compacted gravel, and our guide on how much concrete you need covers the slab that goes on top.
Here's the calculator's math for typical jobs, with pea gravel/#57 at 1.4 tons per yard and crushed stone at 1.5. The last column adds 10% for compaction and settling, which is what most contractors order.
| Project | Size and depth | Cubic yards | Tons (pea/#57) | Tons (crushed) | Tons to order (+10%, pea/#57) |
|---|---|---|---|---|---|
| Garden path | 3 × 30 ft, 2 in | 0.56 | 0.78 | 0.83 | 0.86 |
| Walkway | 4 × 40 ft, 3 in | 1.48 | 2.07 | 2.22 | 2.28 |
| Shed pad | 10 × 12 ft, 4 in | 1.48 | 2.07 | 2.22 | 2.28 |
| French drain | 1 × 50 ft, 12 in | 1.85 | 2.59 | 2.78 | 2.85 |
| Dog run | 10 × 20 ft, 3 in | 1.85 | 2.59 | 2.78 | 2.85 |
| Patio base | 12 × 12 ft, 4 in | 1.78 | 2.49 | 2.67 | 2.74 |
| Single driveway | 12 × 50 ft, 4 in | 7.41 | 10.37 | 11.11 | 11.41 |
| Single driveway | 12 × 50 ft, 6 in | 11.11 | 15.56 | 16.67 | 17.11 |
| Long driveway | 12 × 100 ft, 6 in | 22.22 | 31.11 | 33.33 | 34.22 |
A couple of things stand out. The shed pad and the walkway need the same amount of stone, even though one looks twice as big. And going from 4 to 6 in on a 50 ft driveway adds more than 5 tons. At the calculator's default of $45 a ton, that's the difference between about $467 and $700 in stone, before delivery.
Bagged gravel at home centers usually comes in 0.5 cu ft bags. That's 54 bags per cubic yard, so bags only make sense for small jobs: a path under half a yard, filling low spots, or topping up an existing bed.
For anything bigger, bulk delivery is cheaper per ton and far less work. A few practical points:
Gravel compacts. Crushed stone with fines can lose noticeable depth once it's run over with a plate compactor or a car, and rounded stone settles into soft soil. Excavations are also rarely perfectly even. The usual allowance is 5 to 10% extra, and the gravel calculator page recommends the same.
A leftover half ton is easy to use: fill a low spot, top up a path, or keep it for next year's driveway maintenance. Being a half ton short means paying a second delivery fee.
If you're also covering beds with bark or wood chips, our mulch calculator uses the same depth-based math, just without the tons.
A 12 × 50 ft single driveway needs about 10.4 tons of #57 or pea gravel at 4 in deep, and about 15.6 tons at 6 in. With crushed stone at 1.5 tons per yard, those numbers are 11.1 and 16.7 tons. Add 5 to 10% for compaction.
Most gravel weighs about 1.4 to 1.5 tons (2,800 to 3,000 lb) per cubic yard. Pea gravel and #57 stone are near 1.4 tons, crushed stone near 1.5, and dense limestone can reach 1.7 tons per yard. Wet stone weighs more.
At 2 in deep, a ton of pea gravel or #57 covers about 116 sq ft. At 3 in, it's about 77 sq ft, and at 4 in about 58 sq ft. Crushed stone covers slightly less per ton because it's denser.
Most bagged gravel comes in 0.5 cu ft bags, so it takes 54 bags to make one cubic yard (27 cu ft). That's why bags only make sense for small jobs. Anything over about half a yard is usually cheaper as bulk delivery.
Buy it however your supplier prices it, but convert first so you can compare quotes. Multiply cubic yards by the stone's density (about 1.4 for pea gravel) to get tons, or divide tons by density to get yards.