Volume & tonnage estimator
Gravel calculator
Tell it the shape of the area, how deep you want the stone, and it returns the volume in cubic yards — plus cubic feet, cubic metres, US tons, bag counts and a cost estimate. Mix your units freely: a driveway measured in feet with a depth given in inches works exactly the way you would write it on paper.
Everything is calculated in your browser as you type. Nothing is sent anywhere, and there is no sign-up.
How much gravel do I need?
The whole question comes down to one multiplication: area × depth = volume. Measure the surface you are covering in feet, decide how deep the stone should sit, convert that depth into feet as well, and multiply. The answer lands in cubic feet, and bulk stone is sold by the cubic yard, so you divide by 27.
A worked example. A parking pad 20 ft long and 12 ft wide is 240 square feet. At 4 inches deep — that is 4 ÷ 12 = 0.333 ft — the volume is 240 × 0.333 = 80 cubic feet, or 80 ÷ 27 = 2.96 cubic yards. At a typical gravel density of 1.4 tons per cubic yard, that is about 4.15 US tons. Order three yards and you have a sensible margin.
The three numbers worth memorising. One cubic yard = 27 cubic feet. One cubic yard of gravel weighs roughly 1.3–1.5 US tons. One cubic yard fills 54 of the half-cubic-foot bags sold at big-box stores — which is why bagged stone stops making financial sense somewhere around half a yard.
Converting cubic feet to cubic yards
A cubic yard is a cube three feet on every side, so it holds 3 × 3 × 3 = 27 cubic feet. To go from cubic feet to cubic yards, divide by 27. To go the other way, multiply by 27. The calculator shows both at once so you can sanity-check a quote written in either unit.
Metric conversions follow from the same definition: one cubic foot is 0.0283 m³, and one cubic yard is 0.7646 m³. If your plans are drawn in metres, switch the unit dropdowns to m or cm and read the m³ line.
Coverage: what one cubic yard actually covers
Because 1 yd³ is 27 ft³, the square footage it covers is simply 324 divided by the depth in inches. That single fact produces the whole table.
| Depth | 1 cubic yard covers | 1 US ton covers |
|---|---|---|
| 1 in | 324 sq ft | 231 sq ft |
| 2 in | 162 sq ft | 116 sq ft |
| 3 in | 108 sq ft | 77 sq ft |
| 4 in | 81 sq ft | 58 sq ft |
| 6 in | 54 sq ft | 39 sq ft |
| 12 in | 27 sq ft | 19 sq ft |
Pea gravel calculator notes
Pea gravel is the rounded 3/8-inch stone people use for patios, playgrounds, dog runs and the gaps between stepping stones. Running it through the calculator is no different from any other aggregate — pick the Pea gravel preset, which drops the density to about 1.35 tons per cubic yard because the rounded shape packs a little less densely than angular crushed stone.
What does change is the depth you should ask for. Pea gravel does not lock together, so a thin layer scatters and a thick layer feels like walking in sand. Two inches over a compacted base is the usual compromise for a walkway; three inches is common for a patio or fire-pit surround. Beds that are meant to be walked on benefit from an edge restraint — without one you will be topping up every spring no matter how carefully you calculated.
3/4 gravel and other sizes
"3/4 gravel" is shorthand for crushed stone that passes a 3/4-inch screen, sold in most of the United States as #57 stone. It is the default for driveways, drainage layers and paver bases because the angular faces knit together and the voids between stones still let water through. Figure roughly 1.4 tons per cubic yard.
A quick map of the sizes you will be quoted:
- Stone dust / screenings — under 1/4 in, used as a setting bed under pavers.
- Pea gravel, 3/8 in — rounded, decorative, comfortable underfoot.
- #57, 3/4 in — the workhorse: driveways, French drains, paver base.
- Crusher run (0–3/4 in with fines) — compacts to a hard surface, does not drain; wrong choice for a drain, right choice for a driveway base.
- #4 / 1–2 in — deep base layers and erosion control.
- 2–4 in and larger — ditch lining and rip-rap; see the river rock calculator for decorative grades in this range.
Gravel for a French drain
A French drain is a trench, not a surface, so the maths is a straight box: length × trench width × trench depth. Switch the calculator to a rectangle, put the trench length in Length, the trench width in Width, and the depth of stone in Depth.
Take a standard run: 100 ft long, a 12-inch-wide trench, backfilled with 18 inches of stone. That is 100 × 1 × 1.5 = 150 cubic feet, or 5.6 cubic yards — about 7.8 tons of #57 stone. If a 4-inch perforated pipe runs the full length, it displaces roughly 11 cubic feet, bringing the stone down to about 5.1 cubic yards. Most people order the full 5.6 and use the surplus elsewhere; the pipe deduction only matters on long runs.
Three practical points the arithmetic will not tell you. Use washed #57 or a similar clean, angular stone — crusher run and anything with fines will silt up and defeat the drain. Wrap the trench in filter fabric before the stone goes in, folding it over the top before you backfill. And if the trench is capped with soil or sod rather than left as exposed stone, subtract that capping depth from the figure you type into Depth, or you will over-order.
Buying: bulk, bags and what the truck brings
Bulk stone is quoted by the ton in most of the country and by the cubic yard in some regions — the calculator gives you both so you can compare quotes on equal terms. A standard tandem dump truck carries somewhere around 10–14 tons, and many yards apply a minimum order or a flat delivery fee, so a single yard delivered can cost nearly as much as three.
Bagged stone is priced per 0.5 cubic foot at most home centres. At 54 bags per cubic yard, the crossover point where bulk delivery wins is usually somewhere between a quarter and a half of a yard. Bags still win when you cannot get a truck to the spot, or when you only need to patch a washout.
Common questions
How many cubic yards of gravel do I need for a 10 ft × 10 ft area?
At 3 inches deep: 100 sq ft × 0.25 ft = 25 cubic feet = 0.93 cubic yards, about 1.3 tons. At 4 inches it rises to 1.23 cubic yards (1.73 tons), and at 2 inches it drops to 0.62 cubic yards.
How many tons is a cubic yard of gravel?
Between about 1.3 and 1.5 US tons for most dry, loose aggregates — the calculator defaults to 1.4. Wet stone is heavier, washed rounded stone is lighter, and quarries differ by rock type. Since you are usually billed by weight, get the density from the yard you are actually buying from and type it into the density box.
How deep should gravel be on a driveway?
A new driveway is normally built in layers: 4–6 inches of larger base stone, then 3–4 inches of a top course such as #57 or crusher run, for 8–12 inches total on typical soils. Resurfacing an existing driveway needs far less — 2–3 inches of fresh top course. Calculate each layer separately and add the results.
Does the calculator handle circles and irregular shapes?
Yes. Switch an area block to Circle and enter the diameter — the area is π × (diameter ÷ 2)². For an irregular yard, add several area blocks and approximate the shape with rectangles and circles; the volumes are summed before the depth is applied. A half-circle is simply a circle with the result halved, so enter it as a circle and halve the yardage yourself, or approximate it as a rectangle of the same footprint.
Should I add extra for compaction?
If the stone will be plate-compacted or rolled, yes — angular crushed stone typically loses around 5–10% of its loose volume. Decorative pea gravel that is simply raked level needs no allowance. The compaction / waste field applies the percentage to the whole volume, so put 10 in it and every output rises by a tenth.
Where do these density numbers come from?
They are typical trade figures for dry, loose-delivered material, published in the ranges landscape suppliers quote. They are deliberately presented as editable estimates rather than authoritative constants, because the real number depends on rock type, moisture and how the yard loads its trucks. For anything where being 15% out would matter, ask your supplier for their tons-per-yard figure and override the preset.