Gravel Calculator

How much gravel do I need?

One cubic yard of gravel covers about 108 square feet at 3 inches deep and weighs roughly 1.4 to 1.7 tons, or 2,800 to 3,400 pounds. To size any job, multiply the area in square feet by the depth in feet, divide by 27 to get cubic yards, then multiply by the material density to get tons. A cubic yard is 27 cubic feet, so the coverage figure is just 27 divided by the depth in feet.

A 10 ft by 20 ft driveway apron finished at 3 inches deep needs 1.85 cubic yards, which is about 2.6 tons of crushed stone at 105 lb/ft3, or 100 half-cubic-foot bags if you are buying bagged material. At $45 per cubic yard, that is roughly $83 of stone before the delivery charge. Add the usual 10 percent for settling and spillage and the order becomes about 2 cubic yards.

The two inputs that move the answer most are depth and density. Doubling the depth doubles the volume, and gravel sold damp and compacted weighs 15 to 25 percent more than the same stone dry and loose. Set the depth from the project table below, pick the material preset that matches what you are buying, and confirm both the density and the price unit with your supplier before ordering.

Gravel tons to cubic yards conversion table

Suppliers sell gravel by the cubic yard or by the ton, and the two are not interchangeable without a density figure. Most gravel falls between 1.4 and 1.7 tons per cubic yard as delivered, so the table brackets both ends of that range. Use the 1.4 column for dry, loose, uniformly graded stone and the 1.7 column for damp, well-graded, or compacted material.

Coverage assumes a 3 inch finished depth. At 1 inch one cubic yard covers 324 square feet, at 2 inches 162 square feet, at 4 inches 81 square feet, and at 6 inches 54 square feet. Tons here are US short tons of 2,000 pounds.

Gravel and aggregate density reference

Density is what turns volume into weight, and it varies with stone type, gradation, and moisture. The figures below are approximate dry, loose densities in pounds per cubic foot with their tons-per-cubic-yard equivalents, and they match the material presets in the calculator above.

These are approximate engineering values for dry, loose material. Wet stone runs 15 to 20 percent heavier and compacted material in place is denser still, which is why supplier quotes by the ton usually work out closer to 1.4 to 1.7 tons per cubic yard than to the dry figures above. Whenever a supplier gives you a density for the specific product, use theirs.

Recommended gravel depth by project

Depth drives the total more than any other input, and the right depth depends on load, drainage, and whether the gravel is structural or decorative. These are the depths most contractors build to.

The depths above are finished, compacted depths. Crushed stone loses roughly 15 to 20 percent of its loose depth once it is compacted, so order 15 to 20 percent above the finished volume if you need the surface to still meet grade after rolling.

Related calculators

Groundwork usually needs a grade as well as a quantity. These three cover the slope side of the same jobs.

• Slope calculator

  Grade a driveway or a gravel pad so water sheds off it: percent grade, ratio, and fall per foot from rise and run.

• Pipe slope calculator

  A French drain only works if the pipe falls. Check the minimum slope for the pipe diameter you are bedding in the stone.

• Ramp slope calculator

  If a gravel path is part of an accessible route, check its running slope against the 1:12 ADA maximum.

Worked example: a 10 by 20 ft gravel driveway

Here is the full calculation for a single-car driveway apron, 10 ft wide by 20 ft long, finished at 3 inches of crushed stone at 105 lb/ft3.

1. Area: 10 ft x 20 ft = 200 square feet.
2. Depth in feet: 3 in divided by 12 = 0.25 ft.
3. Volume: 200 sq ft x 0.25 ft = 50 cubic feet.
4. Cubic yards: 50 divided by 27 = 1.85 cubic yards.
5. Weight: 50 cubic feet x 105 lb/ft3 = 5,250 pounds, or 2.6 tons.
6. Bags: 50 cubic feet divided by 0.5 cu ft per bag = 100 bags.
7. Cost: 1.85 cubic yards x $45 per cubic yard = about $83 of material, plus a typical $50 to $150 delivery charge.

Add 10 percent for compaction and spillage and the order becomes 2.04 cubic yards, or about 2.9 tons. Most yards sell in half-yard increments, so you would order 2 to 2.5 cubic yards. At 100 bags the bagged option would cost $400 to $800, which is why anything above roughly half a cubic yard is worth buying in bulk.

How to calculate how much gravel you need

The calculator handles the unit conversions, but the underlying method is short enough to check by hand, and worth understanding when a supplier quotes in different units than you measured in.

1. Measure the area: length x width for rectangles, or pi x radius squared for circles. Break irregular shapes into rectangles and add them up.
2. Choose the finished depth from the project table above, in inches.
3. Convert the depth to feet by dividing the inches by 12.
4. Multiply area in square feet by depth in feet to get cubic feet, then divide by 27 for cubic yards.
5. Multiply cubic feet by the material density in lb/ft3 to get pounds, then divide by 2,000 for US short tons.
6. Multiply the volume or the weight by your supplier's unit price, and add 10 percent for settling, spillage, and uneven subgrade.

Understanding gravel coverage and quantities

Gravel is the default material for drainage, base layers, and low-cost surfacing, and every one of those jobs is priced on volume rather than area. That is why an accurate estimate needs three numbers: the area you are covering, the finished depth, and the density of the stone you are buying. Change any one of them and the total moves proportionally. Common materials include pea gravel, crushed stone, river rock, limestone, and decomposed granite, and they differ enough in density that the same volume can vary by 15 percent in weight, which matters when you are buying by the ton.

• Driveways and parking areas: Gravel drives are cheap to build and drain well, but they only stay flat if they are built in compacted layers. A new drive needs 8 to 12 inches total, and a resurfacing job needs 2 to 3 inches of fresh stone raked into the existing surface.
• Garden paths and decorative beds: Loose decorative stone at 2 to 3 inches over landscape fabric suppresses weeds and drains after rain. Deeper than 3 inches is wasted material that traps leaf litter and becomes hard to walk on.
• Drainage and French drains: Washed clean stone with no fines keeps voids open so water can move through the trench to the pipe. A typical French drain uses a 2 inch bed under the pipe and 4 to 6 inches of cover over it.
• Base layers for pavers, sheds, and slabs: A compacted crushed stone base of 4 to 6 inches gives pavers, shed floors, and small slabs a stable, free-draining foundation. Extend the base beyond the finished edge so the perimeter does not slump.

Practical tips for ordering gravel

• Order 5 to 10 percent more than the calculated volume for settling, spillage, and uneven subgrade, and closer to 20 percent if the material will be mechanically compacted.
• Check whether the quote is per cubic yard or per ton before comparing suppliers. At 1.4 tons per yard, $40 per ton and $56 per yard are the same price.
• Ask for washed clean stone in drainage work and graded crusher run where the surface has to compact. The two are not interchangeable even at the same nominal size.
• Lay landscape fabric under decorative gravel so the stone does not sink into the soil and weeds do not push through.
• Compact driveway gravel in 2 to 3 inch lifts with a plate compactor rather than in one deep pass, or the lower material will never lock together.
• Confirm delivery access and the minimum order. Most yards charge $50 to $150 per load and will not deliver less than a full yard, so small jobs cost more per yard than the headline price.

Frequently asked questions about gravel calculation

The numbers people most often need before ordering, answered up front.