Gravel Calculator

How the gravel calculator works

Area x depth gives volume; density gives weight. The calculator multiplies length x width x depth to get cubic feet, converts to cubic yards, then multiplies by the density of your gravel type — crushed stone and limestone about 1.4 tons per yard, pea gravel and sand about 1.3, crushed granite about 1.5.

Depth guidance: 3 inches is standard for a driveway, 2 inches for a garden path. Add 5% for compaction and uneven ground. For anything over a cubic yard, bulk delivery is far cheaper per yard than bags.

Laying a garden bed? Try the pea gravel calculator or the mulch calculator.

Worked example: a 20 ft by 10 ft driveway

Take a driveway 20 ft long and 10 ft wide, covered with crushed stone 3 inches deep, with the calculator’s usual 5% waste allowance. Here is the same maths the calculator does, step by step, so you can check its result by hand.

Step 1 – volume in cubic feet. Depth in feet is 3 / 12 = 0.25 ft, so the volume is 20 x 10 x 0.25 = 50 cubic feet.

Step 2 – cubic yards. One cubic yard is 27 cubic feet, so 50 / 27 = 1.85 cubic yards.

Step 3 – waste allowance. The calculator adds the 5% you entered: 1.85 x 1.05 = 1.94 cubic yards to order.

Step 4 – weight in tons. Crushed stone weighs 1.4 tons per cubic yard in this calculator, so 1.94 x 1.4 = 2.72 tons.

Step 5 – bags. Each bag holds 0.5 cubic feet, and the volume with waste is 50 x 1.05 = 52.5 cubic feet, so 52.5 / 0.5 = 105 bags. That is why the calculator’s note says bulk is far cheaper for anything over a cubic yard: 105 bags is a lot of lifting and a lot of plastic. If you enter a price per cubic yard, the bulk cost is simply 1.94 times that price – at $50 per cubic yard, for example, that is $97.20.

Measure twice before you order. Lengths and widths are easy to over- or under-estimate on a driveway that is not a neat rectangle. Measure in two or three places, use the largest length and width, and let the 5% waste allowance cover the uneven spots and the edges that need extra stone. If you change the gravel type, only Step 4 changes: pea gravel and sand use 1.3 tons per cubic yard, crushed granite uses 1.5, and limestone uses 1.4, the same as crushed stone.

How much gravel for a 10 ft wide driveway at 3 inches deep?

The table below uses the same method – volume from length, width and 3 inches of depth, then 1.4 tons per cubic yard for crushed stone – before any waste allowance is added. Add 5% to the cubic yards and the tons if you want the amount to order.

How much gravel for a patio or walkway

A patio or a walkway uses the same calculation as a driveway, only the depth is usually thinner. Two inches is enough for a path or a patio that will carry foot traffic and garden furniture, while a driveway needs 3 inches because cars are heavier. The worked example below uses a 12 ft by 8 ft patio, 2 inches deep, with crushed stone, a 5% waste allowance and a price of $50 per cubic yard, so you can follow every step and check it against the calculator above.

Step 1 – volume in cubic feet. Depth in feet is 2 / 12, so the volume is 12 x 8 x 2 / 12 = 16.00 cubic feet. Step 2 – cubic yards. One cubic yard is 27 cubic feet, so 16.00 / 27 = 0.59 cubic yards. Step 3 – waste allowance. The calculator adds the 5% you entered: 0.59 x 1.05 = 0.62 cubic yards to order. Step 4 – weight in tons. Crushed stone weighs 1.4 tons per cubic yard in this calculator, so 0.62 x 1.4 = 0.87 tons (1,742 lb). Step 5 – bags and cost. The volume with waste is 16.00 x 1.05 = 16.80 cubic feet. Each bag holds 0.5 cubic feet, so 16.80 / 0.5 = 33.6, rounded up to 34 bags, and at $50 per cubic yard the bulk cost is $31.11.

Changing the gravel type changes only the weight, because the volume stays 16.00 cubic feet (0.62 cubic yards with waste). The table below uses the densities in the calculator above – crushed stone and limestone 1.4 tons per cubic yard, pea gravel and sand 1.3, and crushed granite 1.5 – and the calculator returned each weight when the same 12 ft by 8 ft patio was run with that type.

For a walkway, measure the length in the same way and use the same 2 inch depth. A narrow path is easy to under-order because the edges spill, so keep the 5% allowance even on a small job, and order bulk rather than bags when the patio is larger than about a cubic yard – 34 bags is already a lot to carry.