Playground Safety Surfacing Calculator
Get a general planning estimate of surfacing depth and volume from your play area and the fall height of your tallest equipment.
How this calculator works
The calculator looks up a required depth from fall height and material, using the taller of the two nearest table steps so it never under-estimates depth, then converts area and depth into a volume:
// simplified rule of thumb, general estimate only depth_in = lookup(fall_height_ft, material) // rounds up to the next depth tier volume_cuft = area × (depth_in / 12) cubic_yards = volume_cuft / 27
For example, engineered wood fiber commonly runs about 9 in of depth for a 6 ft fall and 12 in for an 8 ft fall in general planning tables — a fall height in between, like 7 ft, rounds up to the 8 ft tier's 12 in depth rather than interpolating, so the estimate stays on the safe side.
Worked example
A 20 ft × 15 ft play area (300 sq ft), 7 ft fall height, engineered wood fiber:
- Depth: 7 ft rounds up to the 8 ft tier → 12 in.
- Volume: 300 × (12 ÷ 12) = 300 cu ft.
- Cubic yards: 300 ÷ 27 ≈ 11.1 cu yd.
General depth guidance by material
These are general planning figures only — see the disclaimer above.
| Fall height | Wood fiber | Rubber mulch | Sand |
|---|---|---|---|
| Up to 4 ft | 6 in | 6 in | 6 in |
| Up to 6 ft | 9 in | 6 in | 9 in |
| Up to 8 ft | 12 in | 9 in | 12 in |
| Up to 10 ft | 12 in | 9 in | 12 in |
| Up to 12 ft | 12 in | 12 in | 12 in |
Fall heights above 12 ft are outside what loose-fill surfacing is typically rated for at all — taller equipment usually needs engineered unitary surfacing (poured-in-place rubber, rubber tiles) instead, sized by a professional.
Measuring your play area
- Play area — measure the full use zone around equipment, not just the footprint of the equipment itself; use zones typically extend several feet beyond the equipment on every side.
- Fall height — use the tallest designated play surface across all equipment in the area, not an average.
- Depth — always measure and maintain depth after installation and settling, not just at initial fill.
Frequently asked questions
Why does surfacing depth depend on fall height, not just play area?
Surfacing cushions the impact of a fall, and how much cushioning that takes scales with how far something falls, not with how much ground is covered. Area determines total volume; fall height determines how deep it needs to be.
Engineered wood fiber vs rubber mulch vs sand — what are the tradeoffs beyond depth?
Wood fiber is affordable but decomposes and needs top-up. Rubber mulch absorbs shock better per inch and doesn't decompose, but costs more and can get hot in the sun. Sand is cheap but drains poorly and needs more depth for the same protection.
How often does loose-fill surfacing need to be topped up?
Regular raking is worth doing weekly to monthly in busy areas, since traffic displaces material from high-use spots. A full top-up is commonly recommended annually or once measured depth falls below the required minimum.
Where do I find the specific fall-height rating for playground equipment?
Check the manufacturer's installation manual or spec sheet. For older or unlabeled equipment, a CPSI-certified playground safety inspector can measure and determine the applicable fall height and required depth.