Gravel Calculator

Tip: crushed stone with fines, sold as crusher run or road base, packs down hard. Round pea gravel rolls underfoot and is better for drainage and paths than driveways.

Worked example

A 20 ft by 10 ft parking pad covered 4 inches deep is 200 square feet x 4 / 12 = 66.7 cubic feet.

66.7 / 27 = 2.47 cu yd. At 1.4 tons per cubic yard, that is about 3.46 tons, which is how most quarries and landscape yards price it.

In 0.5 cubic foot bags the same job would take 134 bags, so bulk delivery is the practical choice.

How to calculate gravel

Multiply length by width in feet, then by depth in inches divided by 12. That gives cubic feet. Divide by 27 for cubic yards. Quarries and landscape yards often sell by the ton, so multiply cubic yards by the weight of the stone you are buying.

For a circular area, use 3.14 x radius squared for the area. For a driveway with a curve, break it into straight sections and estimate the curve as a rectangle of its average width.

How much does gravel weigh?

Most gravel and crushed stone weighs between 1.3 and 1.5 tons per cubic yard, depending on the rock and how wet it is. 1.4 is a good default. Some typical figures:

• Pea gravel: about 1.3 to 1.4 tons per cubic yard.
• Crushed stone, 3/4 inch: about 1.35 to 1.45.
• Crusher run and road base with fines: about 1.4 to 1.6, more once compacted.
• River rock: about 1.3 to 1.5.

Your supplier can give you the exact figure for their material. Enter it above to get tons.

Recommended depths

• Garden paths: 2 to 3 inches over landscape fabric.
• Patio and paver base: 4 to 6 inches of compacted crushed stone.
• Driveways: 6 to 12 inches total, laid in layers with larger stone at the bottom and finer stone on top.
• Under a concrete slab: about 4 inches.

Compacted gravel takes up less space than loose gravel. When a base will be compacted, many contractors order 10% to 20% more than the finished depth calls for.

Building a gravel driveway in layers

A long-lasting gravel driveway usually has three layers. The bottom is 4 to 6 inches of large stone, about 2 to 4 inches across, for drainage and strength. The middle is 4 inches of smaller crushed stone. The top is 2 to 3 inches of fine crushed stone or crusher run that packs into a smooth surface. Calculate each layer separately with its own depth and add the tons.

Edge the driveway so the stone does not spread into the lawn, and crown the middle slightly so water runs off the sides.

Ordering tips

Most dump trucks carry 10 to 15 tons. Many suppliers charge the same delivery fee for a partial load, so combining orders, such as base stone and topping, can save money. Have the load dumped as close to the work area as the truck can safely reach, and keep it off septic fields and soft lawns.

Choosing the right stone

The stone you choose matters as much as the quantity. Angular crushed stone locks together when compacted, which makes it the right choice for driveways, paver bases and anywhere that carries weight. Round stone such as pea gravel and river rock stays loose. It drains well and looks good in paths, borders and dry creek beds, but it shifts underfoot and under tires.

Size is given as the largest stone in the mix. 3/4 inch clean stone has no fines and drains freely, which makes it good for drainage trenches and under sheds. Crusher run, also called dense grade or road base, includes stone dust that fills the gaps and packs hard. Ask your supplier for local names, since they vary by region.

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Results are estimates, not a contractor quote. Check quantities with your supplier before you order, and follow local building codes.