How the Gravel Calculator Works
Gravel is sold by the cubic yard (or cubic meter) and by the ton. To buy the right amount for a driveway, a path or a garden bed, you need the volume of the space, and then the weight of the stone that fills it. The Gravel Calculator works out both from the size of the area and the depth.
What you enter
- The area, as a rectangle (length and width), a circle (diameter), or a number of square feet or square meters.
- The depth of the gravel, in inches or centimeters.
- The material. Each has its own typical weight.
- Extra for compaction and waste (optional), as a percent.
- The price of a ton or a tonne (optional), to find the cost.
The formulas
volume (cubic feet) = length x width x depth (inches) / 12 cubic yards = cubic feet / 27 weight (tons) = cubic yards x tons per cubic yard circle area = 3.1416 x (diameter / 2) x (diameter / 2)
A cubic yard is 3 ft x 3 ft x 3 ft = 27 cubic feet. Standard gravel weighs about 1.4 US tons per cubic yard (2,800 pounds). The extra allowance is added to the volume: for 10% extra, the volume is multiplied by 1.10.
Worked example: 20 ft by 10 ft, 3 inches deep
| Step | Calculation | Result |
|---|---|---|
| Area | 20 x 10 | 200 sq ft |
| Volume | 200 x 3 / 12 | 50 cubic feet |
| Cubic yards | 50 / 27 | 1.85 cubic yards |
| Weight | 1.85 x 1.4 | 2.59 tons (5,185 lb) |
| With 10% extra | 2.59 x 1.10 | 2.04 cubic yards, 2.85 tons |
If the gravel costs $40 a ton, the 2.85 tons cost about $114.
The amount for 100 square feet
| Depth | Cubic yards per 100 sq ft | Tons per 100 sq ft | Tons for 200 sq ft |
|---|---|---|---|
| 2 in | 0.62 | 0.86 | 1.73 |
| 3 in | 0.93 | 1.30 | 2.59 |
| 4 in | 1.23 | 1.73 | 3.46 |
| 6 in | 1.85 | 2.59 | 5.19 |
| 8 in | 2.47 | 3.46 | 6.91 |
Chart: tons needed for 200 square feet
Each block is about 0.17 tons. Your depth of 3 inches is green. The amount grows in a straight line with the depth.
2 in ██████████ 1.73 tons 3 in ███████████████ 2.59 tons 4 in ████████████████████ 3.46 tons 6 in ██████████████████████████████ 5.19 tons 8 in ████████████████████████████████████████ 6.91 tons
Chart: how far one ton goes
The deeper the layer, the smaller the area that one ton covers. Each block is about 2.9 sq ft.
2 in ████████████████████████████████████████ 115.7 sq ft 3 in ███████████████████████████ 77.1 sq ft 4 in ████████████████████ 57.9 sq ft 6 in █████████████ 38.6 sq ft 8 in ██████████ 28.9 sq ft
The weight of different materials
The weight of a cubic yard depends on the material, the size of the stones and how wet they are. These are typical values in US tons per cubic yard. To make the differences easier to see, the bars start at 1.0 and each block is 0.0125.
River rock ████████████████████████ 1.30 Pea gravel and sand ████████████████████████████ 1.35 Gravel and decomposed granite ████████████████████████████████ 1.40 Crushed stone ████████████████████████████████████ 1.45 Road base and limestone ████████████████████████████████████████ 1.50
Ask your supplier for the weight of the material that you will buy. A load that is wet can weigh more than a dry one.
How deep should gravel be?
| Use | Typical depth |
|---|---|
| Garden path or a bed | 2 to 3 inches (5 to 8 cm) |
| Patio base | 4 inches (10 cm) |
| Driveway | 4 to 6 inches (10 to 15 cm), in layers |
| Drainage trench | Depends on the pipe. Follow the plan |
Metric units
When you choose meters, the calculator changes everything to feet and inches, and shows the volume in cubic meters (1 cubic yard = 0.7646 cubic meters) and the weight in tonnes (1 US ton = 0.9072 tonnes, and 1 tonne = 1,000 kg). The price is then for one tonne.
Tips
- Add 10% to 15%. Gravel packs down when it is spread and pressed, and some is lost.
- Measure the real shape. For a curved path, split it into a few rectangles, calculate each and add the results.
- Prepare the ground. Take out the grass and the soil, and level the ground before you put the gravel in. A layer of landscape fabric keeps the stones out of the soil.
- Check the delivery. A truck often carries about 10 to 15 tons, and a small load can be delivered in bags or by the bucket.
What this calculator does not include
- The gravel that goes below the surface of a deep base, such as a fill of a big hole.
- The fabric, the edging and the delivery fee.
- The exact weight of your gravel. It uses a typical value for each material.
This tool gives an estimate for planning and shopping. Check the amount and the weight with your supplier before you order.