Every gravel order comes down to three numbers: how many square feet you are covering, how deep you want it, and what the material weighs. Get those three and the arithmetic is a minute’s work. The reason people find it confusing is that the answer has to travel through three different units — you measure in feet and inches, stone is sold by the cubic yard or the ton, and the conversion between yards and tons depends on which stone you picked.
Here is the whole method in one line: area in square feet × depth in feet ÷ 27 = cubic yards, then cubic yards × density = tons. Everything below is that sentence explained, with the shortcuts contractors actually use and three worked examples.
The Three Steps
- Measure the area in square feet. Length times width for a rectangle. For an irregular shape, break it into rectangles and add them up — that is exactly what a professional does, and it is accurate enough. For a circle, radius times radius times 3.14.
- Convert to cubic yards using the 324 shortcut. One cubic yard spread 1 inch deep covers 324 square feet. So coverage per yard at any depth is 324 divided by the depth in inches. Divide your square footage by that number and you have cubic yards. (The long way — square feet times depth in feet, divided by 27 — gives the same answer.)
- Convert cubic yards to tons using the material’s density. Most suppliers sell by the ton. Multiply cubic yards by the tons-per-yard figure for your stone: 1.5 for crushed stone, 1.4 for gravel, 1.35 for pea gravel, 1.5 for river rock, 1.55 for crusher run, 1.5 for sand, 1.1 for topsoil, 1.65 for riprap.
That is it. The gravel calculator runs these three steps for you, and the stone coverage calculator works the same math backwards if you already know how much material you have and want to know how far it goes.
Coverage and Density at a Glance
| Depth | Sq Ft per Cubic Yard | Typical Use |
|---|---|---|
| 1 in | 324 | Top-dressing an existing driveway |
| 2 in | 162 | Driveway surface course, paver base sand is 1 in |
| 3 in | 108 | Landscape beds, walkways, foundation bands |
| 4 in | 81 | Driveway base course, paver base, shed pads |
| 6 in | 54 | Base on soft ground, heavy-traffic areas |
| 8 in | 40.5 | Full base over clay or poor subgrade |
| Material | Tons per Cubic Yard | Cubic Yards per Ton |
|---|---|---|
| Crusher run | 1.55 | 0.65 |
| Riprap | 1.65 | 0.61 |
| Crushed stone (#57, #67) | 1.50 | 0.67 |
| River rock | 1.50 | 0.67 |
| Sand | 1.50 | 0.67 |
| Gravel (natural, rounded) | 1.40 | 0.71 |
| Pea gravel | 1.35 | 0.74 |
| Topsoil | 1.10 | 0.91 |
Pro tip: Ask your supplier for their conversion factor before you order by the ton. Densities vary a little with stone type and moisture content, and the quarry’s own number for their product is more accurate than any published table.
Three Worked Examples
A gravel driveway, 12 ft × 100 ft. That is 1,200 square feet. A proper build is 4 inches of compacted crusher run base plus 2 inches of #57 surface. Base: 1,200 ÷ 81 = 14.8 cubic yards, × 1.55 = about 23 tons. Surface: 1,200 ÷ 162 = 7.4 cubic yards, × 1.5 = about 11 tons. Two separate orders, two separate materials, about 34 tons total — call it three tandem loads. Check it against the gravel driveway calculator.
A garden path, 3 ft × 40 ft. That is 120 square feet at 3 inches of pea gravel. 120 ÷ 108 = 1.1 cubic yards, × 1.35 = 1.5 tons. That is a small load, and many yards will have a minimum charge that makes it cheaper to buy 2 or 3 tons than 1.5. Run it through the pea gravel calculator and read the minimum-load section of the supplier questions guide before you call.
A landscape bed, irregular, roughly 22 ft × 9 ft. Break it into rectangles: say 15 × 9 = 135 plus 7 × 5 = 35, for 170 square feet. At 3 inches of river rock: 170 ÷ 108 = 1.6 cubic yards, × 1.5 = 2.4 tons. At $45 to $130 per ton, river rock is the material where measuring carefully actually saves real money. The river rock calculator handles it, and measuring your yard for stone covers irregular shapes in more depth.
Compaction, Waste, and How Much Extra to Order
The calculated number is the volume of finished, in-place material. Two things push the real order higher.
Compaction is the big one. Dense-graded material like crusher run loses roughly 15 to 20 percent of its loose volume when properly compacted, because the fines settle into the voids. If you want 4 inches of compacted base you have to place closer to 5 inches loose. Open-graded stone like #57 barely compacts at all — it holds 36 to 42 percent voids by design and settles maybe 5 percent — so surface courses need little or no compaction allowance.
Waste is the smaller one: material left in the pile, spread past the edges, lost in the grass, or used to fill a low spot you had not noticed. Ten percent covers it on most jobs.
| Material Type | Add for Compaction | Add for Waste |
|---|---|---|
| Dense-graded (crusher run, #411, 2A, DGA) | 15–20% | 10% |
| Open-graded (#57, #67, drainage stone) | 0–5% | 10% |
| Sand (paver bedding) | 10% | 5% |
| Decorative stone in beds | 0% | 10% |
Pro tip: Round up to the nearest full truckload when you are close. A tandem carries 13 to 15 tons and delivery runs $50 to $150 per load, so ordering 14 tons instead of 11 usually costs less per ton than coming back for a second small delivery later.
Where the Measurement Usually Goes Wrong
The arithmetic is rarely the problem. The inputs are. The most common error is measuring the driveway you want rather than the one you have — people pace it off as “about 100 feet” when it is 118, and end up 15 percent short on a job where the second delivery costs as much as the stone. Use a tape or a measuring wheel, and measure width in three places, because almost no driveway is the same width at the road as it is at the garage.
The second error is treating a project as one depth. A driveway is two materials at two depths, a paver base is 4 inches of compacted crusher run plus exactly 1 inch of concrete sand, and a French drain is a trench volume, not an area times a depth. Calculate each layer separately with its own density figure — the paver base calculator and French drain calculator are built around those specific geometries for exactly this reason.
The third is forgetting that the existing surface is not flat. If you are top-dressing a driveway with ruts and low spots, the ruts will eat material before you achieve any uniform depth at all. Add a little for that, or fill and compact the low spots with crusher run first and then measure for the top-dress.
Bottom Line
Square feet, divided by 324-over-your-depth-in-inches, gives cubic yards. Cubic yards times the density figure gives tons. Add 15 to 20 percent for compaction on dense-graded base material, nothing much on open-graded surface stone, and 10 percent for waste on either. Then round to a sensible truckload. Do the math once for the base and once for the surface — they are different materials at different depths, and treating a driveway as one number is the most common way people end up short. The crushed stone calculator and crusher run calculator will confirm your arithmetic in seconds, and the bulk stone buying guide covers turning that tonnage into an order.
