Gravel Calculator
Cubic yards and tons for driveways, paths, drainage and base layers, with the compaction allowance applied automatically for the materials that actually need it.
How much gravel do I need?
Gravel is ordered by the ton nearly everywhere in the US, so the calculation runs area times depth to get cubic feet, divided by 27 for cubic yards, then multiplied by the weight per yard for that specific stone. Most crushed aggregate sits around 2,800 pounds per cubic yard, which makes one cubic yard roughly 1.4 tons.
At four inches deep, a cubic yard covers 81 square feet. So a 12 by 40 foot driveway, which is 480 square feet, needs about 5.9 cubic yards or 8.3 tons for a four inch layer.
| Area | 2 in | 3 in | 4 in | 6 in |
|---|---|---|---|---|
| 100 sq ft | 0.6 t | 0.9 t | 1.3 t | 1.9 t |
| 500 sq ft | 3.2 t | 4.9 t | 6.5 t | 9.7 t |
| 1,000 sq ft | 6.5 t | 9.7 t | 13.0 t | 19.4 t |
| 2,000 sq ft | 13.0 t | 19.4 t | 25.9 t | 38.9 t |
Tons assume 2,800 lb per cubic yard and include no compaction. Base materials need more, see below.
Compaction is the number most calculators miss
If you are building a driveway or a base layer, the depth you dig is not the volume you order. Crusher run, QP, and any aggregate with fines in it locks together and loses roughly 20 percent of its loose volume when you run a plate compactor over it.
So a driveway that finishes at 6 inches compacted needs about 7.5 inches of loose material going in. Order for the loose number, not the finished one. This calculator adds that allowance automatically when you pick a material that actually compacts, and adds nothing when you pick decorative stone that does not.
Clean decorative stone like pea gravel and river rock has no fines, never gets compacted, and needs no allowance. Adding 20 percent there just means a pile of leftover stone.
Picking the right stone
| Material | lb per yd | Compacts | Best for |
|---|---|---|---|
| Crusher run / QP | 2,800 to 3,200 | Yes, about 20% | Driveway base, under pavers, under walls |
| Crushed stone #57 | 2,600 to 3,000 | No | Drainage, driveway top, behind retaining walls |
| Pea gravel | 2,700 to 2,900 | No | Paths and patios, poor on any slope |
| River rock | 2,600 to 3,000 | No | Decorative beds, dry creek beds |
| Decomposed granite | 2,700 to 3,100 | Yes, about 15% | Firm walking paths, patios |
| Crushed limestone | 2,500 to 2,900 | Yes, about 15% | Base in the Midwest, farm drives |
| Lava rock | 1,000 to 1,400 | No | Lightweight decorative mulch |
| Marble chips | 2,500 to 2,900 | No | Bright decorative beds |
Building a gravel driveway
A driveway that lasts is not one layer of stone. It is three, and skipping the bottom one is why so many gravel drives turn into potholes after two winters.
- Sub base, 4 to 6 inches. Large angular stone, often #3 or 4 inch minus, laid over compacted subgrade and geotextile fabric. This is the structural layer and it spreads the load.
- Base, 3 to 4 inches. Crusher run, compacted. Fills the voids in the sub base and creates a solid working surface.
- Surface, 2 to 3 inches. #57 or similar clean angular stone. This is the layer you see and the one you top up every few years.
Total is 9 to 13 inches of material. For a 12 by 40 foot drive at 10 inches average, that is about 15 cubic yards or 21 tons before compaction allowance. It is a real order, and it is why people are surprised by driveway quotes.
Put fabric down under the sub base. Woven geotextile stops the stone migrating down into soft subgrade, which is the single cheapest thing you can do to extend the life of a gravel drive.
Angular versus rounded
This decides whether your gravel stays where you put it. Angular stone, meaning anything crushed, has flat faces that lock against each other. Rounded stone, meaning anything from a riverbed, behaves more like ball bearings.
Pea gravel looks great in photos and is genuinely unpleasant to maintain on any grade. It migrates downhill, it scatters when a car turns on it, and it does not hold a compacted surface. Use it on flat paths with solid edging, and use crushed stone anywhere a vehicle goes or the ground slopes.
Hauling it yourself
One cubic yard of gravel is about 1.4 tons. That is already at the payload limit of a half ton pickup, and most yards will only load you one yard at a time in a consumer truck for exactly that reason.
A standard tandem dump truck carries 10 to 14 tons, which is roughly 7 to 10 cubic yards. If your job is over about 3 yards, delivery is almost always cheaper than the trips, and considerably cheaper than new rear springs.
Common questions
How many tons of gravel are in a cubic yard?
About 1.4 tons for most crushed stone, based on roughly 2,800 pounds per cubic yard. Crusher run with fines runs a little heavier at up to 1.6 tons, and lava rock is far lighter at around 0.6 tons per yard.
How much gravel do I need for a driveway?
A properly built gravel driveway wants 9 to 13 inches total across three layers. For a 12 by 40 foot drive at 10 inches average that is about 15 cubic yards or 21 tons. A simple top up of an existing drive is 2 to 3 inches, so around 4 yards for the same area.
Should I add extra gravel for compaction?
Yes, but only for materials with fines in them. Crusher run and decomposed granite lose 15 to 20 percent of their loose volume when compacted, so order that much extra. Clean decorative stone such as pea gravel and river rock does not compact and needs no allowance.
How deep should gravel be?
2 to 3 inches for topping up an existing surface, 4 inches for a new path, and 9 to 13 inches in layers for a new driveway carrying vehicles. Going thinner than 2 inches means you will see the ground underneath within a season.
What size gravel is best for a driveway?
Use crusher run for the base because its fines lock together under compaction, and #57 clean angular stone for the surface. Avoid rounded pea gravel on a driveway entirely, it will not stay put under tyres.
These figures are planning estimates. Bulk material weight shifts with moisture and screen size, and suppliers round differently, so confirm the final quantity with your yard before you order.