Sandbox Size Calculator
Plan the perfect backyard sandbox with this sandbox sand calculator: size it by kid count, get the sand volume in cu ft and cubic yards, the 50-lb bag count, a frame lumber takeoff, cover and drainage sizes, and a total cost estimate. 100% client-side — nothing leaves your browser.
1 · Sandbox Dimensions Calculator — Size Advisor by Kid Count
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- Play area
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- Fill depth
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- Note
- Guideline: 16 sq ft/child toddlers, 36 sq ft/child older kids
2 · Sandbox Volume Calculator — cu ft & Cubic Yards
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- Cubic yards
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- Weight (dense sand)
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3 · How Much Sand for Sandbox — Bags & Bulk Calculator
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- Bulk weight
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- Tip
- Over ~1 cu yd, bulk sand from a supplier is far cheaper
4 · Sandbox Lumber Calculator — Frame, Seat Caps & Corner Posts
Also works as a sandbox seat caps calculator and a sandbox frame corner posts calculator — seat-cap board and corner-post counts update with your frame size.
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- Frame height
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- Corner posts (4×4)
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- Seat-cap boards (2×8 × 8 ft)
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5 · Sandbox Cover Size Calculator — Tarp or Wood Lid
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- Wood split-lid (4×8 plywood)
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6 · Sandbox Drainage Calculator — Gravel Base & Landscape Fabric
Use this section as a gravel base under sandbox calculator: it sizes the 2-in crushed layer and the weed-fabric roll for your box size.
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- Landscape fabric
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- Spec
- 2-in gravel base + permeable fabric, no plastic sheeting
7 · How Much Does It Cost to Build a Sandbox?
Edit prices to your local store — defaults are rough US estimates.
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Frequently Asked Questions
How much sand do I need for a sandbox?
For an 8×8 sandbox, multiply length × width × depth in feet: 8 × 8 × 0.5 = 32 cubic feet, which is 1.19 cubic yards (32 ÷ 27). That is 64 standard 50-lb bags of play sand, or 1.60 short tons if you buy in bulk.
How many 50 lb bags of sand for a sandbox?
A 6 ft × 4 ft box at 6 in deep holds 6 × 4 × 0.5 = 12 cubic feet. At 0.5 cubic feet per 50-lb bag, you need exactly 24 bags (round up — buy 25 to cover spillage).
How deep should a sandbox be?
Match depth to the kids: infants 2–3 in, toddlers 2–4 in, preschoolers 4–6 in, grade-schoolers 7 in or more. Most backyard boxes work best at 6–8 in — deep enough to dig, shallow enough to keep the cover on. Under play equipment with a 4-ft fall height, safety codes call for 9 in of sand (12 in for a 6-ft fall).
What size sandbox for 2 kids?
A common guideline is 16 sq ft of play area per toddler and 36 sq ft per older child. Two toddlers → 32 sq ft, so a 6 ft × 6 ft box fits well; two older kids → 72 sq ft, so go 9 ft × 9 ft. Bigger is better for playdates and keeps digging away from the edges.
How many boards for a sandbox frame?
For an 8 ft × 8 ft frame: one stacked layer of 2×6 needs 32 linear feet of board, so 4 standard 8-ft boards; two layers need 8 boards. Add 4 corner posts (4×4, about 12 in long with 6 in buried) and 4 more 8-ft boards of 2×8 if you want flat seat caps.
What size tarp for an 8x8 sandbox?
Add 1 ft of overhang per side: an 8 ft box needs a 9 × 9 ft cover, so buy the next stock size up — a 10 ft × 12 ft tarp. A breathable cover or mesh keeps out animals and leaves without trapping rainwater the way solid plastic does.
Do I need landscape fabric or gravel under a sandbox?
Recommended. Lay permeable landscape fabric under the frame to block weeds. For landscape fabric under sandbox how much do you actually need? An 8×8 box needs about 81 sq ft (a (8+1) × (8+1) sheet), covered by one standard 3×50 ft roll. A 2-in gravel base underneath (10.67 cu ft ≈ 22 bags of 50-lb gravel) drains rainwater so the sand stays dry.
Play sand bags vs bulk sand cost — which is cheaper?
Bags win for small boxes; bulk wins big. That 8×8 example (32 cu ft ≈ 1.19 cu yd) costs 64 bags × $8 = $512 bagged versus roughly $30–$59 for bulk sand at $25–$50 per cubic yard from a landscaping supplier — less than a tenth of the price.
Wood lid or tarp cover — which is better?
A tarp is cheap and light; a wood split-lid doubles as seating and keeps cats out better. As a quick wood sandbox lid plywood sheets calculator: an 8×8 box takes 2 sheets of 4×8 plywood (cut into halves) with 2×4 cleats. Tarp cost ≈ one 10×12 tarp; lid cost ≈ 2 plywood sheets + hinges, roughly 3–5× the tarp.
How many cubic feet of sand per 50 lb bag?
About 0.5 cubic feet — that is the conversion this sandbox sand calculator uses everywhere. To figure out how many bags of sand for sandbox projects you need, divide the sand volume in cubic feet by 0.5: the 8×8 example (32 cu ft) takes 64 bags.
How many cubic yards of sand for a sandbox?
Divide cubic feet by 27. The 8×8 box holds 32 cu ft, which is 1.19 cubic yards. Over about 1 cubic yard, a bulk delivery from a landscaping supplier is far cheaper than bagged sand.
Free tool by NRTechStudio