Play Sand for Sandboxes
Play sand is specifically washed and screened for children -- finer grain, no sharp particles, no silica dust. It's regulated differently from construction sand. Play sand should meet ASTM C33 specifications for gradation and cleanliness. Always buy bags labeled "play sand" from a home center, not construction sand from a landscape supplier.
Standard sandbox depth is 12-18 inches -- deep enough for digging but not so deep that small children can bury themselves. A 6x6 sandbox at 12 inches needs 36 cubic feet of sand, which is 36 bags of 50-lb play sand (each bag is approximately 0.5 cubic feet) or 1.33 cubic yards bulk.
Replace or supplement sandbox sand every 1-2 years. Sand compacts, accumulates debris, and can harbor bacteria over time. Cover the sandbox when not in use to keep animals out.