Pea gravel calculator for Montana
Estimate 3/8 inch rounded stone by the ton for patios, paths, fire pits, and play areas.
Enter your project dimensions
This 3/8 inch rounded stone, named for its pea-like size, weighs 2,800 lb per cubic yard, or 1.4 tons, matching crushed gravel despite its softer feel. Layer depth controls the result: below 2 inches, the ground may show; above 3 inches, the surface gives underfoot like dry beach sand. Enter your measurements in this pea gravel calculator for a ton estimate, then use the listed depths for the two exceptions to the 2 to 3 inch range: play areas and nothing else.
Turn measurements into tons
- Find the area by multiplying length and width, or use the diameter when measuring a circular fire-pit surround.
- For surfaces that will be walked on, allow 2 to 3 inches; playground fall zones need 9 to 12 inches kept in place.
- Divide cubic feet by 27 for cubic yards, then multiply yards by 1.4 for tons.
Material coverage
| Depth | 1 cubic yard covers | 1 ton covers |
|---|---|---|
| 2 inches | 162 sq ft | ≈ 116 sq ft |
| 3 inches | 108 sq ft | ≈ 77 sq ft |
| 4 inches | 81 sq ft | ≈ 58 sq ft |
| 12 inches, play area | 27 sq ft | ≈ 19 sq ft |
| Project | Typical size | Depth | Volume | Weight |
|---|---|---|---|---|
| Patio / seating area | 12 x 12 ft | 3" | 1.3 yd³ | 1.9 tons |
| Garden walkway | 25 x 3 ft | 2.5" | 0.6 yd³ | 0.8 tons |
| Fire-pit surround | 12 ft round | 3" | 1 yd³ | 1.5 tons |
| Playground fall zone | 20 x 20 ft | 12" | 14.8 yd³ | 20.7 tons |
| Dog run | 15 x 8 ft | 3" | 1.1 yd³ | 1.6 tons |
A border keeps gravel contained
Pea gravel moves because its stones are round. A missing border, or one that has settled too low, is behind gravel spreading beyond its intended area. Keep steel, aluminum, timber or paver edging an inch above the surface to contain the stone; edging installed flush allows it to work its way out over a season. Once a grade exceeds about 5%, rain and foot traffic can carry the gravel downhill even with edging. On slopes, install a honeycomb stabilizing grid beneath the gravel, or use angular crushed stone that locks together.
Comparing pea gravel, crushed gravel, and river rock
Pea gravel suits bare feet but shifts under movement. Crushed gravel for walks grips together and handles grades, though its edges are sharper. River rock is larger and decorative, generally used in planting beds rather than walking areas. Cost generally rises in that same sequence. A site can use each material in a different location: crushed gravel on a sloped path, pea gravel at a fire pit, and river rock beside a foundation. Separate calculators make it easy to compare tonnage for one footprint in about a minute.
Field project notes
- For patios, start with 2 inches of compacted screenings to keep chair legs from pressing in, followed by 2 to 3 inches of pea gravel.
- For play areas, the fall-zone specification calls for 9 to 12 inches of maintained material. Refer to the equipment manual. With 12 inches of depth, a ton covers only about 19 square feet, making the calculator more reliable than a visual estimate.
- Fire pits need 3 inches. Because the stone is non-flammable, rain can drain away from the seating area overnight.
- Dog runs use 2 to 3 inches. The rounded pieces are gentler on paws and rinse clean.
- Walkways: Rake the surface level twice each year, then refresh the main traffic line every few seasons with a bucket or two held back for that purpose.
Example calculation: a 12-foot fire-pit circle
For a 12-foot diameter circle, the area is 113 square feet. With a 3-inch layer: 113 x 0.25 = 28 cubic feet = 1.05 cubic yards, which is just below 1.5 tons. Order 1.5, and use the small remaining amount on the high-traffic side next spring.
Pea gravel dimensions and weight
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For a walkway, pea gravel or crushed gravel?
Other calculators
Most patios take less than two tons.
3/8 inch natural pea gravel is sold by the ton, with free delivery.
