Gravel Calculator
Cubic yards and tons of gravel for a drive, path or bed, with the compaction allowance included so the load is not short once it is rolled.
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Results
Working
- area = 30 x 10 = 300 sq ft
- finished volume = 300 x 4 / 12 = 100 cu ft
- loose volume = 100 x 1.15 compaction = 115 cu ft
- cubic yards = 115 / 27 = 4.26 cu yd
- tons = 4.26 cu yd x 2700 lb / 2000 = 5.75 tons
Quick answer
Gravel is area times depth, plus a compaction allowance. Angular stone loses up to a quarter of its loose volume once it is rolled, so ordering the finished volume leaves a drive short. Yards sell by the ton, so the last step is turning cubic yards into weight at roughly 2,700 lb per cubic yard for crushed stone.
tons = area sq ft x (depth in / 12) x compaction / 27 x lb per cu yd / 2000
Worked example
A 30 ft by 10 ft driveway in 3/4 in crushed stone, 4 in deep.
| Order by weight | 5.75 tons — How most yards sell it |
|---|---|
| Order by volume | 4.26 cu yd — 115 cu ft loose |
| Area | 300 sq ft — Rectangle |
| Finished depth | 4 in — After rolling |
| Compaction added | 15% — 15 cu ft extra |
| Sub-base also needed | 10.42 tons — 6 in of crusher run |
| Estimated cost | $258.75 — 5.75 tons x $45 |
| Delivery loads | 1 — At about 20 tons a tipper |
Working
- area = 30 x 10 = 300 sq ft
- finished volume = 300 x 4 / 12 = 100 cu ft
- loose volume = 100 x 1.15 compaction = 115 cu ft
- cubic yards = 115 / 27 = 4.26 cu yd
- tons = 4.26 cu yd x 2700 lb / 2000 = 5.75 tons
The sub-base is the line people skip, and it is usually larger than the surface order. Gravel laid straight onto soil works itself down into it under wheel loads until the drive is mud with stones in it.
Gravel depth and quantity by use
Standard depths, and what 100 square feet takes in crushed stone including a compaction allowance.
| Use | Surface depth | Sub-base | Per 100 sq ft | Weight |
|---|---|---|---|---|
| Decorative bed | 2 in | none | 0.71 cu yd | 0.96 tons |
| Footpath | 3 in | none | 1.06 cu yd | 1.44 tons |
| Patio sub-base | 4 in | none | 1.42 cu yd | 1.92 tons |
| Driveway | 4 in | 6 in | 1.42 cu yd | 1.92 tons |
| Shed or hot tub base | 4 in | 4 in | 1.42 cu yd | 1.92 tons |
Sub-base is compacted crusher run below the surface layer. Multiply the last two columns by your own area over a hundred.
At a glance
| What it does | Turns area and depth into cubic yards and tons, with compaction and sub-base |
|---|---|
| Inputs needed | Area, depth, stone type, what the surface is for |
| Main output | Tons to order |
| Formula | tons = area x depth / 12 x compaction / 27 x density / 2000 |
| Category | Garden & Outdoor |
| Cost | Free, no sign-up, no download |
How to use the Gravel Calculator
- Measure the area. For an irregular shape, break it into rectangles and add the results.
- Pick what the surface is for, which sets a sensible depth and tells you whether a sub-base is needed.
- Choose the stone. Angular crushed stone for anything that takes traffic, rounded stone only for beds.
- Leave the compaction allowance on unless you are ordering loose stone that will not be rolled.
- Order by the ton, since that is how yards price it, and add the sub-base as a separate load.
Frequently asked questions
How many tons of gravel in a cubic yard?
About 1.35 tons for crushed stone, 1.4 for pea gravel and 1.5 for crusher run. Densities vary with moisture and stone size, so treat any tonnage as an estimate and order slightly over.
How deep should gravel be for a driveway?
Four inches of angular surface stone over about six inches of compacted crusher run. The surface layer alone is what fails: without a sub-base the stone works down into the soil under wheel loads.
Why does gravel need a compaction allowance?
Loose angular stone has voids between the pieces. Rolling closes them, which is the point, but it means the finished depth is up to a quarter less than the loose depth you ordered.
Can I use pea gravel on a driveway?
It will not stay put. Rounded stone has no interlock, so tyres push it into ruts and spread it onto the lawn. Angular crushed stone locks together under load, which is why drives use it.
Do I need a membrane under gravel?
Yes, a woven geotextile. It stops the stone migrating down into the soil and blocks weeds from below. It is the cheapest part of the job and the one that decides how the surface looks in three years.
Volumes are exact; weights are estimates, because stone density varies with size, moisture and source. Confirm the density your supplier uses before ordering by weight.
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