Pea Gravel Calculator
Estimate pea gravel for walkways, patios and play areas.
Coming soonGravel Calculator
Use this gravel calculator to work out how much gravel your path, driveway, drainage trench or other area needs. Pick the shape of the area, enter its measurements and how deep you plan to spread the gravel, then press Calculate. You will see the volume in cubic yards and cubic feet, plus a suggested order amount or the number of bags, and the results update as you change values. Results are estimates for planning.
Enter the measurements and depth, then press Calculate to see your results.
Volume needed
Recommended order amount
cubic yards ( cubic meters)
Rounded up to the next 0.25 cubic yard.
Estimated bulk cost:
Bags needed
bags
Rounded up to whole bags.
Estimated bag cost:
Show calculation
How to use this calculator
- Choose US or Metric, then a shape. Pick Rectangle, Circle, Ring or Triangle, or choose Known area if you already know the size of the area.
- Enter the measurements and depth. US sizes are in feet and Metric sizes are in meters. Decimals are fine, such as 12.5. Depth has its own switch: inches or feet in US, centimeters or meters in Metric. The typed value converts when you switch.
- Choose how you are buying. Bulk gives an order amount in cubic yards. Bags gives the number of 0.5 cubic foot bags. Add a price if you would like a cost estimate. Open More options for several identical areas or an extra allowance.
- Press Calculate. If anything needs fixing, every problem is listed at once. After the first calculation, the results update as you change values.
- Use the results. Open Show calculation to see the steps, and use Copy result to save everything.
Formula
Start with the area of the shape. US mode uses feet and square feet; Metric mode uses meters and square meters.
- Rectangle: length × width
- Circle: π × (diameter ÷ 2)²
- Ring: π × [(outer diameter ÷ 2)² − (inner diameter ÷ 2)²]
- Triangle: ½ × base × height
- Known area: the area you enter
US: cubic feet = area × depth in inches ÷ 12 × quantity × (1 + extra ÷ 100)
Metric: cubic meters = area × depth in cm ÷ 100 × quantity × (1 + extra ÷ 100)
A depth entered in feet is converted to inches first (× 12), and a depth in meters to centimeters (× 100).
Cubic yards = cubic feet ÷ 27, and 1 cubic foot ≈ 0.0283168 cubic meters (exactly 0.3048³ m³).
Bags = cubic feet ÷ 0.5, rounded up to a whole bag
The order amount is the cubic yards rounded up to the next quarter yard. We divide by 27 because one cubic yard is 3 ft × 3 ft × 3 ft.
Worked example
A path area measures 10 ft × 10 ft and the gravel will be spread 4 inches deep. (4 inches is just an example.)
- Area: 10 × 10 = 100 sq ft
- Cubic feet: 100 × 4 ÷ 12 = 33.33 cubic feet
- Cubic yards: 33.33 ÷ 27 = 1.23 cubic yards, so an order amount of 1.25 cubic yards
- Bags of 0.5 cubic feet: 33.33 ÷ 0.5 = 66.67, rounded up to 67 bags
How far does gravel go?
The deeper you spread gravel, the less ground it covers. This table shows the area covered by one cubic yard and by one 0.5 cubic foot bag at each depth.
| Depth | Per cubic yard (sq ft) | Per 0.5 cu ft bag (sq ft) |
|---|---|---|
| 1 in | 324 | 6.0 |
| 2 in | 162 | 3.0 |
| 3 in | 108 | 2.0 |
| 4 in | 81 | 1.5 |
| 6 in | 54 | 1.0 |
Common gravel uses and choosing a depth
Gravel is used for paths and patios, drainage and driveways. For paths and patios, the University of California Master Gardeners describe two main kinds (Gravel Pathways in the Garden, E. Millier, UC Master Gardener, Contra Costa Times, 2011, reissued 2020):
- River run (rounded pieces; pea gravel is one example) never packs down completely, so it can be hard to walk on. They suggest it suits a mulch or ground cover better, though it can work for paths and patios if large stones are added to support furniture.
- Crushed stone (angular pieces) packs down into a nearly solid surface, so they consider it more useful for paths and patios with a lot of foot traffic. They add that smaller pieces are easier and more comfortable to walk on.
We have not listed a recommended depth for each use, because we could not confirm one from a source we can name. The right depth depends on the type of gravel, the soil beneath it and what will use the surface, so check with your local extension office or your supplier. Then enter the depth you choose into the calculator above.
Measuring an irregular area
Not every area is a neat shape. Work out its area first, then enter the total as a Known area.
- Split it into simple shapes. Break an L-shaped area into rectangles, find each area, and add them up. Use Show calculation to see the area of each part.
- Use the round shapes. A round area is a Circle, and a ring of gravel around a fire pit is a Ring: enter the outer diameter, and the inner diameter for the area you keep clear.
- Average a slope. If the gravel depth changes steadily from one side to the other, add the shallow and deep depths and divide by 2. Use that average as the depth.
For example, a 12 ft × 8 ft area (96 sq ft) with a 6 ft round area beside it (28.27 sq ft) gives a total area of about 124.27 sq ft.
Assumptions and limitations
- The area is a flat shape with the same depth everywhere. The result is a geometric volume.
- Compaction varies. Crushed gravel can pack down, so the finished layer may be thinner than the loose depth you enter. Use the extra material allowance if you want to plan for that.
- The result is volume only, not weight. Gravel weight per cubic yard varies with the type of stone and its moisture, so ask your supplier for their weight per cubic yard if you buy by the ton.
- Bag counts assume 0.5 cubic foot bags, a size commonly sold for bagged gravel. Check the size printed on the bag. Bags are rounded up to whole bags.
- The bulk order amount is rounded up to the next 0.25 cubic yard, because suppliers often sell in ¼ or ½ yard steps. In Metric mode it is still shown in cubic yards, with its cubic meter equivalent.
- The extra material allowance is your own figure. We do not suggest a specific percentage.
- Results are estimates for planning. Check quantities with your supplier before ordering.
Frequently asked questions
How many bags of gravel are in a cubic yard?
A cubic yard is 27 cubic feet, so it takes 54 bags of 0.5 cubic foot gravel. Check the size printed on the bag, because it can vary by brand and product.
How do I calculate how much gravel I need for a path or driveway?
Choose the shape that matches the area, such as Rectangle for a straight path, enter its measurements, and enter how deep you want the gravel. For an irregular area, work out its total area first and enter it as a Known area.
How many square feet does a cubic yard of gravel cover?
It depends on the depth. One cubic yard covers about 324 square feet at 1 inch deep, 162 at 2 inches, 108 at 3 inches, 81 at 4 inches and 54 at 6 inches.
My supplier sells gravel by the ton. Can I use this calculator?
This calculator gives volume in cubic yards, not weight. Gravel weight per cubic yard varies with the type of stone, how it is graded and how wet it is, and we do not have a reliable published figure to offer. Ask your supplier for their weight per cubic yard, then multiply it by the order amount.
Should I add extra for compaction?
University of California Master Gardeners note that angular (crushed) gravel packs down into a nearly solid surface, so a loose layer can end up thinner once it is compacted. The extra material allowance, under More options, adds whatever percentage you choose. We do not suggest a specific figure.
What is the difference between pea gravel and crushed stone?
University of California Master Gardeners describe two main groups: river run, which is rounded (pea gravel is one example), and crushed stone, which is angular. Rounded gravel never packs down completely, while angular gravel packs into a nearly solid surface. This calculator works for either, because it only calculates volume.