How it works
Volume is the straightforward part: length times width times depth, with the depth converted into the same unit as the plan dimensions. The number that actually matters when you ring a supplier is the weight, because bulk aggregate is sold by the ton rather than by the cubic yard.
Weight comes from the material's bulk density, and bulk density is not the density of the rock. A pile of gravel is stone plus the air between the stones, so what you are really measuring is how well the pieces pack together. Rounded stone of a single size traps the most air and weighs least per yard. Angular crushed stone interlocks a little better. Road base is heaviest of the lot, because it deliberately includes fine material that fills the voids between the larger pieces.
That is why the material selector changes the answer rather than just the label. Pricing a road base job at river rock density under-orders by about 19%, which on a ten ton delivery leaves you nearly two tons short.
What a cubic yard weighs
These are planning figures for dry material. Every one of them moves with stone size and moisture content, and a wet load can run around 10% heavier than the same material dry.
| Material | Tons per yd³ | Tonnes per m³ | Why |
|---|---|---|---|
| River rock | 1.30 | 1.54 | Large rounded stone, most void space |
| Pea gravel | 1.35 | 1.60 | Small rounded stone |
| Crushed stone #57 | 1.35 | 1.60 | Angular, interlocks but stays open |
| Gravel, general | 1.40 | 1.66 | Mixed sizes, the usual default |
| Decomposed granite | 1.45 | 1.72 | Contains fines, packs tighter |
| Road base (crusher run) | 1.55 | 1.84 | Fines deliberately fill the voids |
How gravel is sold, and the unit trap
In the United States aggregate is quoted in short tons and delivered by the ton, and almost every supplier sets a minimum load. Elsewhere the unit is usually the tonne, and occasionally the cubic metre.
Those two conventions cause one specific and expensive mistake. A short ton is 907 kg, not 1,000 kg, so a tonne is about 10.2% heavier than a ton. A quote "per ton" and a quote "per tonne" are not the same quote, and the gap between them is wider than most people's haggling margin. If you are comparing suppliers across that line, convert before you compare.
How far a ton goes
Suppliers and landscapers tend to think in coverage: the ground one ton spreads over at a given depth. For general gravel at 1.40 tons per cubic yard:
| Depth | One ton covers | Depth | One tonne covers |
|---|---|---|---|
| 2 in | 116 sq ft | 50 mm | 12.0 m² |
| 3 in | 77 sq ft | 75 mm | 8.0 m² |
| 4 in | 58 sq ft | 100 mm | 6.0 m² |
| 6 in | 39 sq ft | 150 mm | 4.0 m² |
Halve the depth and you double the area, which is the quickest sanity check there is on a quantity somebody has quoted you.
What to ask about price
The price field starts blank on purpose. Aggregate prices move with fuel, haulage distance and which quarry you happen to be near, so any figure I baked into this page would be wrong for most people and stale for everyone inside a year. Enter what your supplier quotes you and the calculator does the multiplication.
Three things worth asking for separately, because a headline price rarely includes them: the price per ton for the material itself, the delivery charge, and the minimum load. On a small job the short load fee is often the largest single line on the invoice.
Worked example
A 20 ft × 10 ft driveway strip, 4 inches deep, in general gravel, quoted at $45 per ton.
- Convert depth to feet: 4 ÷ 12 = 0.333 ft.
- Volume: 20 × 10 × 0.333 = 66.7 ft³, or 2.47 yd³.
- Weight: 2.47 × 1.40 = 3.46 tons.
- Coverage check: one ton at 4 in covers 58 sq ft, and 200 sq ft ÷ 58 ≈ 3.4 tons, which agrees.
- Cost: 3.46 × $45 = $155.56, before delivery.
Order about 2.47 cubic yards, weighing roughly 3.46 tons, for around $155.56 of material.
Common questions
How deep should a gravel driveway be?
A single topping layer is usually 2 to 4 inches (50 to 100 mm). A driveway built up from subgrade normally uses several compacted layers totalling 6 to 10 inches (150 to 250 mm), often with a coarser base course under a finer top course. This calculator handles one depth at a time, so for a layered build run it once per layer.
How many tons of gravel are in a cubic yard?
About 1.4 short tons for general gravel, which is the same thing as roughly 1.66 tonnes per cubic metre. It runs from about 1.30 tons per cubic yard for loose river rock up to about 1.55 for road base, because the fines in road base fill the air gaps that rounded stone leaves behind.
How much area does a ton of gravel cover?
One ton of general gravel covers about 116 square feet at 2 inches deep, 77 square feet at 3 inches, 58 square feet at 4 inches and 39 square feet at 6 inches. In metric, one tonne covers about 12 square metres at 50 mm, 8 at 75 mm, 6 at 100 mm and 4 at 150 mm. Halve the depth and you double the area.
Why does the weight figure carry a caveat?
Density genuinely varies. Angular crushed stone, rounded pea gravel, and wet versus dry material can differ by 15% or more. Treat the figure here as a solid planning estimate and confirm it with your supplier before ordering a large load.
Should I add extra for compaction?
The volume here is the finished, compacted layer. Loose gravel takes up more space before it is spread and compacted, so suppliers often build a small margin into delivered quantities. Ask whether the volume you have been quoted is loose or compacted, because the two are not interchangeable.
Why is the price field empty?
Because any price I hardcoded would be wrong for most people. Aggregate cost depends on the material, the haulage distance and which quarry is near you, and it moves year to year. Enter the price your supplier quotes and the cost appears alongside the quantities. Ask separately about delivery and the minimum load.