How Much Sand Do I Need for a Sandbox?

The short answer

Sandbox math starts in cubic feet: length × width × (depth in inches ÷ 12). Divide by 27 for cubic yards. Then the magic number for bags: a 50-lb bag of play sand holds about 0.5 cubic feet, so one cubic yard (27 cubic feet) takes 54 bags. A 6×6 ft sandbox at the recommended 6-inch depth: (6 × 6 × 0.5) / 27 = 0.67 cubic yards, × 54 = 36 fifty-lb bags. Round up to the nearest bag and add 10% — sand settles and kids relocate an astonishing amount of it to the surrounding yard.

Square sandbox bag table

Bag counts for the three most common square sizes at 4, 6, and 8 inches of sand. Each cell shows cubic yards, then the number of 50-lb bags (rounded up, before overage).

Round sandbox bag table

For round or octagonal boxes, use the diameter. Same layout: cubic yards, then 50-lb bags, rounded up.

Odd-shaped box? The formula never changes: measure the footprint area in square feet, multiply by depth in feet (inches ÷ 12), divide by 27 for cubic yards, then multiply by 54 for bags. For anything irregular, the sand calculator does the area math for you.

Pick the right depth first

4 inches is the minimum for a toddler box — enough to scoop, and shallow enough that little legs climb in and out easily. 6 inches is the sweet spot for most sandboxes: real digging depth without the frame losing control of the sand. 8 inches or more suits older kids who dig tunnels and pour moats — but every extra inch costs bags fast, as the 8×8 row shows. One note: frame boards should stand at least 2 inches above the finished sand level, or the first enthusiastic digging session exports half the sandbox to the lawn.

Bags vs bulk: the cost breakpoint

Bagged play sand (50-lb bags, typically $4 to $6 each in 2026) wins for small jobs because it is clean, labeled, and easy to haul. But the price per yard is brutal once you scale up: 36 bags for a standard 6×6 box costs roughly $145 to $215. A bulk yard of washed sand from a landscape supplier runs about $25 to $45, plus $50 to $100 for delivery — so the total bulk cost is often$75 to $145, undercutting bags even before the delivery split. The breakpoint: once your table lookup crosses about 20 bags (roughly a third to half a yard), price a bulk yard from a local supplier. One caveat — sand actually labeled “play sand” is rarely sold in bulk, so confirm the bulk product is washed and screened, not dusty masonry sand.

What to buy: play sand, washed and screened

Sandbox sand should be labeled play sand — washed, screened, and low in dust. Skip coarse paver sand (too rough) and dusty masonry or all-purpose sand (too gritty, too much airborne dust). If you want the full rundown of every sand type and what each is for, see our types of sand guide. Whatever you buy, give each bag a shake: clumping is fine (moisture), but visible debris, shells, or a chemical smell means the bag goes back.

Prep the box before the sand

Lay landscape fabric — not plastic sheeting — across the bottom of the frame before the sand goes in. The fabric blocks weeds and keeps soil from migrating up into the sand while letting rainwater drain through; plastic traps water and the box becomes a swamp. A cover (tarp, lid, or fitted cover) is the other essential: it keeps neighborhood cats out and keeps rain from compacting the sand into concrete. Plan to rake the sand annually and top up an inch or two each spring — kids remove more sand than any formula accounts for.

Fill, level, and settle

Cut the bags open at the box and pour — do not haul loose sand across the yard in buckets if you can avoid it. Spread with a garden rake to the target depth, then mist lightly with a hose and rake again: a little moisture settles the sand and knocks down the fine dust from fresh bags. Expect the level to drop an inch or so in the first week as the sand compacts; that is exactly what the 10% overage covers. Check depth with a ruler in a few spots before you call it done — kids find the shallow corners instantly and migrate sand away from them. And keep two or three bags in the garage: the first big rainstorm washes out low spots, and a quick top-up beats a store run.

When to refresh the sand

Plan on topping up 1 to 2 inches every spring — play sand compacts, washes, and walks away on shoes and pails. Once a year, rake the whole box, pull out any debris or toys, and add fresh bags to restore the depth from the tables above. If the sand has turned gray, compacted hard, or smells musty, it is time for a full change-out: shovel the old sand into wheelbarrows (it makes excellent fill or paver-base material) and refill per the chart. A sandbox cover between play sessions roughly doubles the interval between refreshes.

Common mistakes

Ordering exact bag counts. Sand settles and kids export it — add 10% and keep a spare bag or two. Plastic under the sand. See above: swamp. Paver sand in a kids' box. Coarse and dusty; play sand exists for a reason. Too-deep frames. Twelve inches of sand is a wheelbarrow bill, not a sandbox. No cover. An uncovered sandbox is a litter box with better marketing.