How Much Sand for a Sandbox?

The formula

Volume (cu ft) = Length (ft) × Width (ft) × Depth (in) ÷ 12

Bags needed = Volume (cu ft) ÷ 0.5 (for 50 lb bags of play sand)

How much sand by sandbox size

Sandbox size	Depth	Volume (cu ft)	50-lb bags
3×3 ft	6”	4.5	9 bags
4×4 ft	6”	8.0	16 bags
4×6 ft	6”	12.0	24 bags
4×8 ft	6”	16.0	32 bags
5×5 ft	6”	12.5	25 bags
6×6 ft	6”	18.0	36 bags
4×4 ft	8”	10.7	22 bags
4×6 ft	8”	16.0	32 bags

50 lb bag of play sand ≈ 0.5 cu ft. Round up to the nearest bag.

How deep should sandbox sand be?

Depth	Best for
4–5 inches	Toddlers (under 3) — less to swallow, still playable
6 inches	Most children — good for digging and sand castles
8 inches	Older kids who like deep digging projects
10+ inches	Usually unnecessary — adds cost without play benefit

What type of sand to use

Play sand (also called “sandbox sand” or “washed play sand”):

• Washed and screened to remove sharp particles
• Fine grain — easy to mold and sift
• Available at all hardware and garden stores

Avoid:

• Construction sand — too coarse, may contain debris
• Masonry sand — fine but not washed for skin contact
• Beach/river sand — may contain salt, shells, or bacteria
• Silica sand — fine for industrial use but dusty and not recommended for children

Cost estimate

Product	Price range	Coverage
50 lb bag play sand	$5–$8	~0.5 cu ft
60 lb bag play sand	$7–$10	~0.6 cu ft
Bulk play sand (cu yd)	$30–$60	27 cu ft

For a 4×4 sandbox at 6” deep (16 bags), budget $80–$130 for play sand.