Gravel Calculator

What is a gravel calculator?

A gravel calculator works out how much gravel you need for a project, in cubic yards, tons, bags, and cost, before you order. You enter length, width, and depth, pick a material, and it converts area and depth into volume, then volume into weight using that material’s density.

This matters because gravel is not bought by the bag for a driveway or patio, it is bought by volume or weight, usually cubic yards or tons, and the same volume weighs a different amount for different materials. Pea gravel, crushed stone, crusher run, and river rock all have different densities, so a calculator that hides density will give you a wrong tonnage even if the volume is right.

How to calculate gravel

Start with area in square feet, length x width. Multiply by depth in inches, divide by 324, and you have cubic yards. Multiply cubic yards by density and you have tons. One cubic yard is 27 cubic feet, and one 50 lb bag is 0.5 cubic feet, so one cubic yard needs 54 bags.

1. Measure length and width in feet. For an irregular area, split it into rectangles, calculate each one, and add them up.
2. Pick a depth in inches for your project, and pick a material first, because density changes the tons.
3. Calculate cubic yards with length x width x depth / 324.
4. Convert to tons with cubic yards x density, using the density shown in the calculator.
5. Add waste for spillage and uneven ground, and compaction separately for layers that will be compacted, then check bags and cost.

Gravel worked examples

Worked example: a patio 10 feet by 20 feet, 3 inches deep, is (10 x 20 x 3) / 324 = 1.85 cubic yards. At 1.40 tons per cubic yard for crushed stone #57, that is 2.59 tons, or 2.85 tons with 10 percent waste. At $40 per ton, material cost with waste is about $114.

Use the table for a quick check, and use the calculator for your exact size, material, waste, and compaction, because those change the order.

Gravel density: why tons vary

There is no single tons-per-yard number for all gravel. Density depends on material, stone size, and moisture. Wet gravel weighs more than dry gravel, and a quarry’s scale ticket is final for a large order. Use these planning ranges, and confirm with your supplier for a big delivery.

How deep should gravel be?

Depth depends on the project, the soil underneath, and whether the layer will carry vehicles or just feet. Use these starting points, then adjust for your soil and use.

How much area does a yard of gravel cover?

One cubic yard covers 324 square feet at 1 inch deep, 162 square feet at 2 inches, 108 square feet at 3 inches, and 81 square feet at 4 inches. One ton covers about 100 square feet at 2 inches, depending on material. If your area is bigger than that, you need more than one yard, and bulk delivery is usually cheaper than bags.

Bags vs bulk gravel

A 50 lb bag is 0.5 cubic feet, so one cubic yard needs 54 bags. Bags make sense for small jobs under about half a cubic yard, for example topping up a path or a small bed. For anything bigger, bulk delivery is usually cheaper, even after a delivery fee, and it is much faster to spread. Check truck access before you book bulk delivery, because a full dump truck needs room to turn and tip, and soft ground can be a problem after rain.

Gravel layers: driveway, patio, and shed base

For a driveway, build in layers, not one thick loose layer. Start with a compacted crusher run base, 6 to 8 inches, with about 15 percent compaction, then a surface layer of #57 stone, 2 to 4 inches, with about 10 percent compaction. Calculate each layer separately in the gravel calculator, then add them for total tons and cost. A driveway 12 x 50 ft, base 6 inches plus surface 3 inches, needs about 11.11 cubic yards for the base and 5.56 cubic yards for the surface, before waste.

For a patio, plan 4 inches of compacted crusher run base, then 2 to 3 inches of pea gravel or #57 surface, and edge the patio so gravel stays in place. For a shed base, plan 4 inches of compacted crusher run, measure the shed footprint plus a small margin, and check the ground is level before delivery. A shed on soft, uncompacted gravel will settle unevenly.

Waste vs compaction: keep them separate

Waste covers spillage, uneven ground, and edges that are hard to measure. Compaction covers how much a loose layer settles when it is compacted. They are different, and adding them together as one number hides which one you changed. The calculator keeps them separate, so you can set waste for spillage and compaction for a base layer, and see the total to order for each.

Common gravel mistakes

1. Measuring area once, in feet, but depth in the wrong unit, so the volume is off by a factor of 12.
2. Using one density for every material, so pea gravel and crusher run give the same tons, when they should not.
3. Forgetting waste and compaction, then running short on the last load, which costs a second delivery fee.
4. Ordering one thick loose layer for a driveway, instead of a compacted base plus a surface layer.
5. Comparing a price per ton with a price per yard without converting by density.

How to order gravel without getting short

Measure the area twice. Pick the material first, because density changes the tons. Keep waste and compaction separate. Ask your supplier: price per ton or per yard, delivery fee, minimum order, and whether the price is by weight on a scale ticket or by volume. Check truck access, and check whether the delivery can be tipped where you need it, or whether you will have to wheelbarrow it a long way.

Related gravel calculators

Frequently asked questions

Estimate only. Confirm with your supplier before ordering.