Playground mulch calculator
Playground surfacing is safety equipment, not decoration. Size your use zone, pick a depth that meets CPSC guidance, and get the cubic yards of engineered wood fiber (EWF) to order.
EWF needed
What depth does playground mulch need to be?
For public and home playgrounds in the US, the reference standard is the CPSC Public Playground Safety Handbook (publication #325), and most EWF (engineered wood fiber) suppliers test to ASTM F1292 impact attenuation. Practical guidance:
- 9 inches loose EWF is the classic minimum for equipment with fall heights up to about 7 feet — after it settles to ~6 in compacted, it still cushions.
- 12 inches is the safe choice for taller composite sets (8–10 ft decks) and for public-use equipment.
- Top up and “fluff” (re-till) the surface regularly — kicked-out zones under swings and slide exits lose depth fastest.
Size the use zone correctly
The protective surfacing must extend at least 6 feet in every direction from equipment (more in front of swings: 2× the top bar height, front and back). A 7 ft × 8 ft playset needs roughly a 19 ft × 20 ft zone before you add swing clearance — measure the zone, not just the footprint. The calculator's default 20 × 16 ft reflects a compact set with swing extension.
How much EWF is that?
A 20 ft × 16 ft zone at 9 inches loose needs 320 × 9 ÷ 12 = 240 ft³ ≈ 8.9 yd³ (about 4.5 tons). EWF is typically delivered in bulk bags or dump delivery; at ~500 lb/yd³, plan equipment to move it.
Weight note: the calculator uses 500 lb/yd³ (typical 400–600 depending on moisture). A cubic yard of EWF is roughly a quarter ton — a 10 yd³ order is over two tons of material.