How Many Tons of Gravel for a Driveway or Base?

Gravel is the material that trips up the most estimates, and the reason is a unit mismatch built into how it is bought and sold. You measure a driveway in feet and inches, which gives you a volume. The quarry sells it by the ton off a scale, which is a weight. Get the conversion between those two wrong and you are either short a load or paying for tonnage rotting in a pile. I have ordered enough crushed stone to have a feel for it, but the math is what keeps it honest.

Start with volume, always

Every gravel order begins as a volume problem. Volume = length × width × depth, with all three in the same unit. Depth is the one people get wrong, because it is given in inches while length and width are in feet. Convert the depth to feet first: 4 inches is 4 ÷ 12 = 0.333 feet. A driveway 60 feet long and 12 feet wide at 4 inches deep is 60 × 12 × 0.333 = about 240 cubic feet. Divide by 27 to get cubic yards, since a cubic yard is 27 cubic feet, and you land at roughly 8.9 cubic yards.

That cubic-yard figure is the foundation. If you want it without the arithmetic, the

gravel and aggregate calculator

takes your area and depth and gives both cubic yards and tonnage in one shot, with the density already set by material.

Converting volume to tons

Here is the step the unit mismatch forces on you. To turn cubic yards into tons you multiply by the material's density. Crushed stone runs about 1.4 to 1.5 US tons per cubic yard. Pea gravel is a touch lighter, sand is heavier when wet, and screened topsoil or fill varies a lot with moisture. Using 1.45 tons per yard for crushed stone, our 8.9 cubic yard driveway is 8.9 × 1.45 = about 12.9 tons. Round that to 13 tons and you have your order.

This is why a single "tons per square foot" rule of thumb fails: the answer depends on depth and on which material you are spreading. A calculator that carries a density for each material — crushed stone, pea gravel, sand, topsoil, fill — is doing the part that a generic rule cannot.

How deep, and how many courses

A driveway is rarely one uniform layer. Over soft or clay ground I build it in courses. A coarse base course of larger crushed stone, 4 to 6 inches, locks together and carries the load. On top of that goes a 2 to 3 inch finish course of smaller, angular crushed stone that compacts into a tight, drivable surface. Each course is its own volume calculation at its own depth, and the tonnages add up. If you are only refreshing a worn surface, a single 2 to 3 inch top-up may be all you need.

Whatever the depth, remember it is the compacted depth that matters. Gravel arrives loose and fluffy and tightens up as it is rolled or driven on, which is one of the reasons the order needs a margin on top.

Which material, and why it changes the number

"Gravel" is a loose word for several materials that behave differently and weigh differently. Angular crushed stone is my default for a driveway surface because the sharp faces lock together and stay put under tires; it runs about 1.4 to 1.5 tons per cubic yard. Rounded pea gravel looks nice but rolls and migrates, so it suits paths and drainage more than a driving surface, and it is a touch lighter per yard. Sand is heavier than you expect, especially wet, and is usually a bedding or leveling layer rather than a structural one. Screened topsoil and fill vary the most because their weight swings with moisture content.

This is the practical reason a generic "gravel" estimate is risky: the same cubic-yard volume turns into a different tonnage depending on what you are actually spreading, and the density also tells you whether the material will stay where you put it. Pick the material first, let that set the density, and the tonnage follows. The calculator carries a density for each option so you are not guessing at the conversion that drives the whole order.

The 10% margin

I add about 10% to gravel orders, more than I add to concrete. Three things eat into a load: compaction pulls the surface down so you need more material to hit final depth, the subgrade is never perfectly flat so the low spots drink extra, and the edges of a driveway spread and slough unless you have a hard edge to contain them. Ten percent on a 13 ton order is a bit over a ton — cheap insurance against a half-empty driveway and a second trucking fee.

A full worked example

A parking pad, 30 feet by 20 feet, built with a 5 inch base course and a 2 inch top course of crushed stone. Base: 5 inches is 0.417 feet, so 30 × 20 × 0.417 = 250 cubic feet, ÷ 27 = 9.3 cubic yards. Top: 2 inches is 0.167 feet, so 30 × 20 × 0.167 = 100 cubic feet, ÷ 27 = 3.7 cubic yards. Total 13 cubic yards. At 1.45 tons per yard that is 18.9 tons, and with 10% added I order about 21 tons. The

gravel and aggregate calculator

lets you run each course separately and pick the material so the density is right for what you are actually spreading.

The bottom line

Gravel is cheap by the ton and expensive to deliver twice. Measure the area, convert depth to feet, get cubic yards, multiply by the right density for your material, and add 10%. Do that and the truck shows up once with the right amount — which is the whole game on a base or driveway job.