How to use the pea gravel calculator
Choose what the gravel is for and enter the size of the area. For a playground, enter the highest point a child could fall from and the calculator sets the depth for you from the CPSC's safety table, adding the extra needed for compression. For a dog run, patio, path or drainage area, enter the depth you want.
The formula
playground install depth = 9 in maintained ÷ 0.75 (25% compression) = 12 in
cubic feet = area × depth (ft) × (1 + extra)
tons = cubic feet ÷ 27 × 1.35
Worked example: a 20 × 16 ft play area
- Fall height 4 ft: pea gravel is rated to 5 ft at 9 in maintained depth, so it qualifies.
- Install depth: 9 ÷ 0.75 = 12 in.
- Volume: 320 ft² × 1 ft = 320 ft³; with 5% extra 336 ft³ = 12.4 yd³.
- Weight: 12.4 × 1.35 = 16.8 tons. Order bulk delivery; that would be 672 bags.
Playground surfacing depths (CPSC)
| Material | Maintained depth | Protects falls up to |
|---|---|---|
| Shredded/recycled rubber | 6 in | 10 ft |
| Wood chips | 9 in | 10 ft |
| Wood mulch (non-CCA) | 9 in | 7 ft |
| Pea gravel | 9 in | 5 ft |
| Sand | 9 in | 4 ft |
From Table 2 of the CPSC Public Playground Safety Handbook. The depths are after compression; CPSC notes loose fill (except rubber) compresses at least 25%, so you install more and top it up. CPSC also recommends never maintaining less than 9 in of loose fill.
Other uses
- Dog runs: 3-4 in of pea gravel over fabric drains well and is easy on paws. Rinse and rake it regularly; some owners prefer a concrete or turf area for waste.
- Patios and paths: 2-3 in over a compacted base and fabric, with steel or paver edging. Stepping stones set into the gravel make it easier to walk on.
- Drainage: pea gravel is rounded and drains well, but it doesn't lock together. Under foundations and in French drains, angular #57 stone is usually preferred; see the gravel calculator.
Keeping it in place
- Contain it. A border of timbers or plastic edging keeps pea gravel from rolling into the lawn, where it damages mowers.
- Rake high-traffic spots. Under swings and at slide exits gravel gets kicked away fast. Check the depth often and top up.
- Wear mats under swings reduce how much gravel gets displaced.
Questions people ask
How deep should pea gravel be under a swing set?
The CPSC's Public Playground Safety Handbook says 9 inches of pea gravel (measured after it has compressed) protects against falls of up to 5 feet. Loose fill compresses at least 25%, so install about 12 inches to keep 9.
Is pea gravel safe for playgrounds?
For low equipment, yes: CPSC lists it as an appropriate surface. At 9 inches it's only rated for falls up to 5 ft, less than wood chips (10 ft) or shredded rubber at 6 inches (10 ft), so for taller equipment choose a different surface.
How much pea gravel do I need for a 10x10 area?
At 3 inches deep, 25 cubic feet: 0.93 cubic yards, about 1.25 tons, or 50 bags of 0.5 cubic feet. For a playground at 12 inches installed depth it's 3.7 yards, about 5 tons.
How much does a yard of pea gravel weigh?
About 1.3 to 1.4 tons dry. This calculator uses 1.35 tons per cubic yard; damp gravel is heavier.
How deep should pea gravel be for a patio?
2 to 3 inches over landscape fabric, on a compacted base, with edging to hold it in. Deeper than 3 inches is hard to walk on and chairs sink in.
Sources and assumptions
- U.S. CPSC Public Playground Safety Handbook (Pub. 325), Table 2 and §2.4.2.2: 9 in compressed pea gravel protects to 5 ft; loose fill compresses at least 25%
- Vulcan Materials product calculators: pea gravel about 1.35 tons/yd³
- Dog run and patio depths are common landscaping practice, not standards.
Last reviewed 27 October 2026. Every formula on this page is checked against the worked example above in our automated tests. Found a problem? Tell us.