How to Calculate Gravel Cost — Step by Step

The short answer

To work out what gravel costs, measure the area, work out the volume, and add 10% extra for settling. For a 500 square foot bed at 3 inches deep that gives a volume of 125.00 cubic feet, which is 5.09 cubic yards to order, and the gravel costs $254.63 at $50.00 a cubic yard, plus $50.00 delivery, which is $304.63 in total.

The three numbers that matter

The first number is the area, in square feet, measured across the bed or the yard. For this bed that is 500 square feet. The second number is the depth, in inches. A garden bed is about 3 inches deep, so the volume is 500 times 3 divided by 12, which is 125.00 cubic feet.

The third number is the price per cubic yard, which is about $50.00 for pea gravel. The cubic yards are the cubic feet divided by 27, so 125.00 divided by 27 is 4.63 cubic yards. Add 10% extra for settling, and it is 5.09 cubic yards to order. The gravel cost is 5.09 times $50.00, which is $254.63, and the total is $304.63 with delivery, or $0.61 a square foot.

The method

The method is three steps and an addition. One: multiply the area by the depth in feet to get the volume in cubic feet. Two: divide the volume by 27 to get the raw cubic yards, then add 10% extra to get the billable volume. Three: multiply the billable volume by the price per cubic yard to get the gravel cost, then add the delivery to get the total. The extra is the part people forget, and it is the part that leaves the bed short.

Step by step

Step 1: find the area. Measure the bed or the yard in feet, with a tape measure, and multiply the length by the width. For this bed that is 500 square feet.

Step 2: find the volume. Multiply the area by the depth in feet. For this bed that is 500 times 3 divided by 12, which is 125.00 cubic feet. The depth in feet is the depth in inches divided by 12, so 3 inches is 0.25 feet. A garden bed is about 3 inches deep, and a driveway is 4 to 6 inches.

Step 3: find the billable volume. Divide the volume by 27 to get the raw cubic yards, then add 10% extra. For this bed that is 125.00 divided by 27, which is 4.63 cubic yards, and 4.63 times 1.10 is 5.09 cubic yards to order.

Step 4: price the gravel and add the delivery. Multiply the billable volume by the price per cubic yard, then add the delivery. For this bed that is 5.09 times $50.00, which is $254.63, and $254.63 plus $50.00 delivery is $304.63 in total. The check is the cost per square foot: $304.63 divided by 500 is $0.61, the number to compare between beds and between quotes. If a quote is far from $0.61 a square foot for the same bed, ask what is different.

Step 5: check bags against bulk. Divide the volume by 0.5 to get the bags, then multiply by $5.00. For this bed that is 125.00 divided by 0.5, which is 250 bags, and 250 times $5.00 is $1,250.00. Bulk costs $304.63, so bulk wins by $945.37.

The worked example

A homeowner is covering a 500 square foot front bed, and the yard charges $50.00 a cubic yard for pea gravel, and $50.00 for delivery. The volume is 500 times 3 divided by 12, which is 125.00 cubic feet. The raw volume is 125.00 divided by 27, which is 4.63 cubic yards, and with 10% extra it is 5.09 cubic yards to order. The gravel costs 5.09 times $50.00, which is $254.63, and the total is $304.63, or $0.61 a square foot. Bags would cost $1,250.00, so bulk wins by $945.37. The gravel weighs 14,259 pounds, or 7.13 tons, so it comes on a truck, not in a car boot.

A bigger yard, and other round numbers

Some gravel jobs are worth knowing by heart. A 1,000 square foot yard is 1,000 times 3 divided by 12, which is 250.00 cubic feet, and 10.19 cubic yards to order, so the gravel costs $509.26 and the total is $559.26, or $0.56 a square foot. A 2-inch bed instead of 3 inches is 83.33 cubic feet, and the total falls to $219.75, or $0.44 a square foot. Gravel at $65.00 a cubic yard costs $331.02, and the total is $381.02.

Working backwards from a budget

To find how much area a budget covers, subtract the delivery from the budget, then divide what is left by the price per cubic yard, then divide by the extra, then work out the area. A $500 budget minus the $50 delivery leaves $450. Divide that by $50.00 a cubic yard, and it buys 9.00 cubic yards. Divide by 1.10, and it is 8.18 cubic yards of raw volume, which is 883.64 square feet at 3 inches deep. A $1,000 budget buys 1,865.45 square feet.

Common mistakes

The most common mistake is ordering the raw volume, not the billable volume. A 500 square foot bed is 4.63 cubic yards raw but 5.09 cubic yards to order, so ordering the raw volume leaves the bed short by 0.46 cubic yards. The second mistake is forgetting the delivery, which is $50.00. The third is measuring the straight-line distance instead of the bed. The fourth is using the bag price for a whole bed, which is $1,250.00, not $304.63. The fifth is guessing the depth: 2 inches looks the same as 3 inches on the day, but the fabric shows through in a year.

The verdict

A 500 square foot bed at 3 inches deep costs $304.63 in gravel: 125.00 cubic feet, which is 5.09 cubic yards to order, at $50.00 a cubic yard, plus $50.00 delivery. Measure the area, work out the volume, and add 10% extra. Check the numbers yourself on the gravel cost calculator, compare the cover with the gravel vs mulch comparison, or price the mulch with the mulch cost calculator.