Gravel Calculator: Tons and Cubic Yards, Layer by Layer

Measure the ground before you ring the quarry

A gravel calculator is only as good as the three numbers you feed it. Length and width go in feet or metres. Depth goes in inches or centimetres: I measure depth in inches, never in feet, because a 4 left in a feet box orders twelve times the stone.

• Rectangles (drives, parking pads, paths): length × width.
• Round areas (fire-pit circles, tree rings): measure straight across. The tool asks for the diameter, because that is what your tape reads; a diameter typed into a radius formula gives four times the area.
• Triangles (the flare where a drive meets the road, wedge corners): base × height ÷ 2.
• L-shapes and turnarounds: split them into rectangles, circles and triangles and enter each as its own area. They add up into one order. An area you already know, from a plan or a survey, goes in as a single number.
• Uneven ground: probe the dug-out bed or the old stone at five or six spots and use the average depth.

Loose versus compacted: the step most calculators skip

Stone arrives loose and gets thinner when you compact it. A crushed base with fines loses a fifth to a third of its loose depth under a plate compactor or roller, so a 6 in finished base ordered as 6 in of loose stone leaves you short. Order the base loose, not compacted.

The Penn State Center for Dirt and Gravel Roads places driving surface aggregate (DSA) 8 in loose and rolls it to 6 in, or 6 in loose to 4½ in. That is 1⅓ times the compacted volume, a 33 % allowance. Their field check for a lane: tons = length (ft) × width (ft) × 0.04 at 8 in loose. Ohio DOT Item 411 caps a compacted lift of crushed aggregate at 6 in, so a thicker base goes down in lifts, each one compacted.

Each layer in the calculator gets its own loose-to-compacted allowance. My starting points: 0 % for decorative cover nobody compacts, 10 % for pea gravel that settles under foot, 20 % for a plate-compacted crushed base, 33 % for dense-graded road base. A separate waste allowance goes on top, and the two multiply: 10 % and 5 % make ×1.155, not ×1.15.

The gravel calculator formula on real jobs

A US (short) ton is 2000 lb, or 907.18 kg; a metric tonne is 1000 kg, about 10 % more. Most loose gravel runs 1.4–1.7 US tons per cubic yard, so one ton is roughly 0.6–0.7 yd³ (0.714 yd³ at 1.4). These are jobs I would actually price, each rechecked step by step:

The fire pit shows why the diameter matters: the same 12 typed as a radius gives 4.19 yd³ instead of 1.05.

How much a cubic yard of gravel weighs

One figure of 1.4 tons per yard for everything undercounts riprap and road base and nearly doubles lava rock. These are loose, dry, as-delivered densities; the tool starts from the default column and lets you type your yard's own number.

Wet stone weighs more, and so does stone after compaction: Ohio DOT pays compacted crushed stone at 3800 lb per cubic yard in place, about 1.9 tons. Use that figure to check a finished base, never to order loose stone.

How far a ton or a yard of gravel goes

Suppliers often quote 100, 80 and 60 ft² per ton at 2, 3 and 4 in. Those are rounded down from the exact figures and leave a sensible cushion.

Building it up in layers

A driveway that lasts is a stack, not a pile. On firm soil a typical build-up is 6–9 in in total: 3–4 in of #3 at the bottom, 2–3 in of #57 in the middle, 1–2 in of #8 or pea gravel on top. Heavier traffic or soft soil needs more. Pea gravel never goes under a driveway: round stones roll, and only angular crushed stone locks into a base. Give the finished surface a crown of ½–¾ in per foot so water runs off instead of sitting in ruts.

The calculator lets you stack up to four layers, each with its own stone, density, finished depth and allowance. It draws the build-up to scale, with a ruler and a label on each layer showing the loose depth to order, so a wrong depth is visible at a glance. Presets cover a three-layer drive, a DSA farm lane, a garden path and a metric patio, all editable.

Worked example, a 60 × 12 ft drive (720 ft²):

1. #3 base, 4 in, +20 %: 720 × 4 ÷ 12 × 1.2 = 288 ft³ = 10.67 yd³ → 14.92 US tons at 1660 kg/m³.
2. #57 middle, 3 in, +20 %: 216 ft³ = 8.00 yd³ → 11.19 US tons.
3. Pea or #8 top, 2 in, no allowance: 120 ft³ = 4.44 yd³ → 6.29 US tons at 1680 kg/m³.
4. Total: 23.11 yd³ = 32.41 US tons. At an example price of 38 per US ton that is 1,231.49; with 14-ton loads it is 3 trucks, or 4 if each stone comes on its own truck.

Stone sizes and where each belongs are in crushed stone sizes explained; the full driveway build, from subgrade to crown, is in gravel driveway layers; for garden work read pea gravel patios and paths.

Ordering: tons or yards, rounding and truckloads

Quarries weigh stone and price it per ton; many landscape suppliers load by the bucket and price per cubic yard. Ask which, and enter the price in that same unit. The tool takes a price per US ton, per metric tonne, per yd³, per m³ or per bag, and you set the currency sign yourself, so a price per short ton is never applied to tonnes, a 10 % error either way.

Round up the way stone is sold: to the next ½ yd³ or to whole US tons, to whole m³ or whole tonnes, or to bags of a size you type (1000 kg by default, the usual 1 t bulk bag). Each layer is rounded on its own. The cost is worked out on the rounded order, which is what you will pay, or on the exact amounts when rounding is off.

Truck capacity depends on the truck and on local weight limits, so ask your hauler for the number. I start at 14 US tons for a tandem (10 t in metric); the tool also takes a volume limit for light stone that fills the box first. Loads are rounded up: 28 tons in 14-ton loads is exactly 2 trucks, not 3. The tool also shows how many trucks you would need if every stone came on its own.

Already have a pile? Open the What will it cover? tab and reverse the sum. Five US tons of crushed stone at 4 in covers about 289.5 ft²; 2 t of pea gravel at 5 cm covers 23.8 m². Give it the amount and your area instead, and it returns the depth.

Mistakes I see on first gravel orders

• Depth typed in feet, or a diameter typed as a radius (×12 and ×4 the stone).
• Ordering a base by its compacted depth instead of its loose depth.
• Mixing up US tons and metric tonnes: about 10 % off.
• One "1.4 tons per yard" for everything: riprap and dense road base run 1.6–2.0, lava rock about half.
• Laying a thick base in one lift. Compact in lifts of no more than about 6 in.
• Round pea gravel as a driveway base: it rolls.
• No crown, so water stands on the drive and softens the base.

Behind the numbers: densities, rounding and test cases

Every job is worked in metres internally, with exact unit factors: 1 ft = 0.3048 m, 1 in = 2.54 cm, 1 yd³ = 27 ft³ = 0.764554857984 m³, 1 US ton = 2000 lb = 907.18474 kg. Weight is loose volume × loose density; allowances multiply; results round only for display, and orders and truckloads always round up. Densities are the defaults in the weight table, set inside published ranges. Moisture and gradation move them, so use your supplier's figure when you have one: the density box takes kg/m³, US tons per yd³ or lb/ft³. Switching between feet and metres keeps what you typed, because each field remembers its own unit; only empty fields switch. A negative, non-numeric or absurdly large entry gets an error on that field and is left out of the result until you fix it. The calculator runs entirely in your browser and sends nothing anywhere; your last job is remembered in this browser only.

I check the tool against cases worked out by hand:

Limits: it does not know your soil, drainage or traffic, and a gravel calculator cannot replace your quarry's gradation sheet.