What this gravel calculator works out
Gravel is sold by weight but measured on site by volume, and that mismatch is where most orders go wrong. You measure a driveway in feet, your supplier quotes in tons delivered, and somewhere between the two you have to convert cubic feet to cubic yards and then apply a density figure that changes with the type of stone. This gravel calculator does all three steps at once and gives you the tonnage to order, the cubic yards for suppliers who quote by volume, and an estimated delivered cost.
It also adds a waste allowance, which is the step people most often skip. Gravel settles into soft ground, disappears into ruts, and spreads past the edges you marked out. Ordering the exact calculated figure almost always means a second trip.
How much gravel do I need?
The quantity depends on three things: the area you are covering, how deep the layer needs to be, and how heavy your chosen stone is per cubic yard. Area and depth are yours to measure. Depth is the one worth getting right, because it is the number that most affects whether the finished surface lasts.
| Project | Recommended depth | Typical stone |
|---|---|---|
| Driveway, single layer | 4 in | Crusher run or #57 |
| Driveway, full build | 8–12 in in two or three layers | Base course then #57 |
| Walkway or garden path | 2–3 in | Pea gravel |
| Patio base under pavers | 4–6 in compacted | Crusher run |
| Drainage trench | 6–12 in | #57 washed stone |
| Decorative bed | 2 in | River rock or lava rock |
For a full driveway build, run the calculator once per layer rather than entering the total depth in one go. The base course and the top course are usually different materials with different densities, so a single calculation would use the wrong weight for one of them.
Tons versus cubic yards: which one do you order?
Both figures describe the same pile of stone. A cubic yard is a volume — 27 cubic feet, roughly the load of a small pickup bed filled level. A ton is a weight. Converting between them needs the density of the specific material, and that is why the calculator asks you to pick a gravel type rather than assuming one.
- Crushed stone and #57 gravel run about 1.4 tons per cubic yard. This is the default and the safest assumption for general-purpose gravel.
- Pea gravel is slightly lighter at roughly 1.35 tons per cubic yard because the rounded stones pack with more air between them.
- Crusher run is the heaviest common option at about 1.5 tons per cubic yard, since the stone dust in it fills the voids.
- River rock comes in near 1.25 tons per cubic yard, and decorative lava rock is far lighter at around 1.1.
If your supplier publishes their own density, use it. Quarries vary by region and a difference of 0.1 tons per cubic yard on a 20-yard order is two extra tons — real money, and a real difference to whether the load fits on one truck.
Measuring an area that is not a rectangle
Most driveways and beds are not neat rectangles. Rather than trying to be clever, break the shape into pieces you can measure and run the calculator once per piece:
- L-shaped areas: split into two rectangles at the inside corner, calculate each, then add the tonnages.
- Circular beds: multiply the radius by itself, then by 3.14, to get the area in square feet. Enter that figure as the length and use 1 as the width.
- Triangles: take the base times the height and halve it, then enter that as the length with a width of 1.
- Curved driveways: measure the width at several points, take the average, and multiply by the centre-line length.
The depth mistake that doubles your order
Depth is entered in inches while length and width are in feet, and mixing those up is the single most common error. Entering 4 where the field expects feet rather than inches would order twelve times the gravel you need. The calculator handles the conversion for you, so enter the depth exactly as you would say it: four inches is 4.
What gravel actually costs
Delivered gravel typically runs between $25 and $70 per ton in the United States, depending on the stone and how far it travels. Decorative stone sits well above that range. The delivery charge is usually a flat fee per trip rather than per ton, which is why a single larger order almost always beats two smaller ones.
Bagged gravel from a home improvement store is convenient for tiny jobs and expensive for anything else. A 50 lb bag holds about 0.5 cubic feet, so covering even a small patio takes dozens of bags at several times the bulk price per ton. The calculator shows a bag count so you can see the crossover point for yourself — once you are past roughly 40 bags, bulk delivery is almost certainly cheaper.
Allow for compaction, not just waste
Loose gravel loses volume when it is compacted. A layer that measures four inches straight off the truck can settle to three and a half once it has been rolled and driven on. For a decorative bed this does not matter. For a driveway or a paver base, where the finished depth is structural, add the waste allowance and plan on the compacted depth being 10–15% less than the loose depth you spread.
The default 10% waste allowance in this calculator covers ordinary spillage and settling on reasonably firm ground. Raise it to 15–20% if the ground is soft, muddy, or heavily rutted, because the first inch of gravel will simply disappear into it.