How much gravel do I need?
Area times depth gives the volume; density turns it into tons.
Multiply area by depth for the volume, then multiply by 2,400-2,900 lb per cubic yard for the weight. A 33 x 10 ft path at 4 in needs 4.1 cubic yards, over five tons.
The calculation
Volume is the easy part. Density is the delicate one, because loose gravel runs 2,400-2,900 lb per cubic yard depending on stone size, type and moisture. Any figure quoted to the pound is false precision.
Depth by use
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| Use | Depth | Notes |
|---|---|---|
| Decorative garden gravel | 1.5-2 in | Over membrane, or it sinks |
| Footpath | 2-3 in | Smaller stone compacts better |
| Driveway | 4-6 in | Over a compacted sub-base |
| French drain | 4-8 in | Coarse washed stone |
Gravel per square foot
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| Depth | cu ft per sq ft | lb per sq ft |
|---|---|---|
| 2 in | 0.167 | 16 |
| 3 in | 0.25 | 24 |
| 4 in | 0.333 | 32 |
| 6 in | 0.5 | 48 |
The membrane is not optional
Without a geotextile membrane underneath, gravel mixes into the soil within months: some sinks, mud comes up, and you end up with a dirty path rather than a gravel one. The membrane costs little next to topping up the stone every couple of years.
Bulk or bags
The threshold is around half a ton. Below that, bags are convenient. Above it, bulk is cheaper and far less work: five tons is 200 bags, which is two days of carrying.
Sources and methodology
The calculation is volumetric and density is an editable parameter, because it varies with the aggregate. Depths reflect common practice; for driveways, check your supplier's advice on the compacted sub-base.
Frequently asked questions
How much gravel do I need for a driveway?
For 33 x 10 ft at 4 in deep, about 4.1 cubic yards including waste, which is over 5 tons. At 2 in you would need half that.
How much does a cubic yard of gravel weigh?
2,400 to 2,900 lb depending on stone size and type. A mid-range figure of 2,600 lb is commonly used.
How many 50 lb bags in a cubic yard?
About 52 bags at 2,600 lb per yard. Above half a yard, bulk delivery is better value and far less carrying.
How deep should gravel be for a driveway?
4 to 6 inches, over a compacted sub-base. Without the base, gravel sinks under vehicle weight.