Gravel Driveway Calculator

How the gravel driveway calculator works

A 50 × 12-ft gravel driveway takes 17.5 tons of gravel for a new install — 11.67 tons of base and 5.83 tons of surface. That's 600 sq ft covered 4 inches deep for the base (7.78 cubic yards) and 2 inches deep for the surface (3.89 cubic yards), 11.67 cubic yards in total at 1.5 tons per cubic yard, including a 5% waste factor. A refresh of the same driveway is surface-only: 5.83 tons.

A proper gravel driveway is two layers, not one:

1. Base layer — 4 inches (10 cm) of crushed roadbase or 3/4" minus. This is the structural part. Compacted to about 90% with a vibratory plate. Without a proper base, the surface layer disappears into the soil within a year.
2. Surface layer — 2 inches (5 cm) of 3/4" minus (graded for traffic) or decorative gravel (for aesthetics). This is the layer you see and drive on. Replenished every 3–5 years as it migrates and packs in.

Refresh installs are surface-only — replacing the migrated 1–2" of gravel that's worn down or scattered. Skip the base layer if your existing driveway has a solid foundation.

The full layer stack, and where the calculator's two layers fit

The two-layer model above is the standard residential build and it is what the calculator sizes. Contractors on soft ground, long drives, or anything that will see a delivery truck build a three-layer stack instead, with a coarse stone at the bottom that bridges weak subgrade. The stone sizes below are US aggregate numbers; regional names vary ("Class II base," "crusher run," "MOT Type 1," "¾ minus") but the sizes are the same idea.

Map that onto the calculator like this. On decent soil, the tool's base depth is your compacted crushed-stone structural layer and its surface depth is your ¾″-minus wearing course — 4 inches and 2 inches by default. If you are building the full three-layer stack, add the sub-base and base depths together and enter the total as the base depth: 4″ of #3 plus 4″ of #57 means entering 8. The tonnage arithmetic is the same because the calculator applies one average density, 1.5 tons/cu yd, across the whole order.

One counterintuitive point about the surface layer. It is tempting to top a driveway with clean, washed, attractive stone. Do not — clean stone has no fines, so it never locks up, and a driveway surfaced in it stays loose and rutted forever. The surface course wants dirty stone: ¾″ minus, crusher run, or dense-graded aggregate, where a spread of sizes down to rock dust fills every void and compacts into a nearly solid crust. Pea gravel and river rock are the two worst driveway surfaces sold, for exactly this reason.

Tonnage per 100 feet of driveway

Driveways are long, so it helps to think per hundred feet. These are new installs at the default 4″ base + 2″ surface, 5% waste, 1.5 tons/cu yd — read straight off the calculator:

A tandem-axle dump truck carries roughly 10–14 cubic yards, so a 100-foot 12-foot-wide driveway is about two truckloads. Widths matter more than people expect: going from 10 to 12 feet is a 20% larger order across the whole length. Ten feet is fine for a straight run; twelve gives you room to open a car door onto gravel rather than lawn; anything over fourteen is usually a turnaround or parking apron rather than a driveway, and those are worth measuring separately and adding in.

Edging and geotextile

Gravel migrates. It is loose stone on a slope with cars turning on it, and without a restraint at the edges it will spread sideways into the lawn for years until the middle is bare. Edging is the single cheapest thing you can do to reduce how often you re-top.

Geotextile is the other high-leverage, low-cost item, and it is not optional on clay, silt, or anything that stays soft in spring. A woven separation fabric between subgrade and stone stops two failures at once: your expensive stone sinking down into the soil, and soil fines pumping up into the stone every time a wheel loads it. At roughly $0.30–$0.60 per square foot it is a small fraction of the stone cost and it routinely doubles how long a base lasts. Roll it out with 12–18 inches of overlap at seams, running up the sides of the excavation, and never pull it tight — it should lie relaxed so it can deflect under load.

Crown, drainage, and the regrading cadence

Every gravel driveway needs a crown: the centre sits 1–2% higher than the edges — about ¾ to 1½ inches of rise across a 12-foot width — so water sheds to both sides instead of running down the wheel tracks. Water running lengthwise is what carves ruts and, in a freeze-thaw climate, what lifts the surface apart. On a sloped drive, add cross-slope or shallow water bars to break the run into short segments so nothing gets up to scouring speed.

Do the regrading when the surface is damp, not bone dry and not saturated — damp material knits together under a drag or box blade, dry material just moves around, and wet material smears. This is the closest thing to a free maintenance trick on this page.

Worked example: a 100 × 10-ft rural driveway on soft ground

Enter 100 ft × 10 ft, new install, and open Advanced options to set base depth to 6 inches (the soil is heavy clay) with the surface at 2 inches and 5% waste. Area is 1,000 sq ft. The base is 1,000 × 0.5 ft × 1.05 = 525 cubic feet, which is 19.44 cubic yards or 29.17 tons. The surface is 1,000 × 0.1667 ft × 1.05 = 175 cubic feet, 6.48 cubic yards or 9.72 tons. Total: 25.93 cubic yards, 38.89 tons.

That is three tandem-axle loads, and on clay it should also include about 1,000 square feet of woven geotextile — call it $300–$600 — laid before any stone arrives. Note how much of the order is base: three-quarters of the tonnage is the layer nobody ever sees. That ratio is the whole argument of this page. Underbuilding the base to afford prettier surface stone is the standard way to end up rebuilding in three years.

Worked example: refreshing a tired 60 × 10-ft driveway

Switch the project type to Refresh and enter 60 ft × 10 ft. The base layer drops out entirely and only the surface is calculated: 600 sq ft × 0.1667 ft × 1.05 = 105 cubic feet, or 3.89 cubic yards — 5.83 tons. One small delivery, an afternoon with a rake, and a rented plate compactor.

Before you order it, make sure a refresh is what you actually need. Push a screwdriver or a length of rebar into a rut. If it stops within a few inches, the base is intact and fresh surface stone will fix things. If it sinks easily, or the ruts fill with standing water and the edges are spongy in spring, the base has failed or been contaminated — and topping it with 5.83 tons of new stone buys you one dry season before the same ruts return in the same places. There is no way to fix a failed base from above; it has to be dug out, separated with fabric, and rebuilt.

What else the calculator doesn't price

• Excavation and disposal — a new driveway means stripping 6–10 inches of sod and topsoil, and that spoil has to go somewhere. On a 600 sq ft drive that is 11–18 cubic yards of material to move.
• Compactor rental — a vibratory plate runs $60–$80 a day and is not optional on the base. Compact in lifts of 3–4 inches; a plate only densifies the top few inches, so one deep dump leaves the bottom half loose.
• Culvert or apron — where the drive meets a public road there is usually a permit, a required culvert size, and sometimes a paved apron specified by the municipality. Check before you dig.
• Slope limits — above about 10% grade, loose surface stone migrates downhill regardless of what you do. Steep sections generally want a bound surface or a stabilisation grid.

Frequently asked questions

For other gravel uses — drainage, walkways, patio bases — see the general gravel calculator, which lets you pick the material density directly.