Sandbox Sand Calculator
Sandbox sand volume, bag count, and weight from box size.
What it does
Sandboxes eat more sand than the box suggests. An 8 in fill across a 5 by 5 ft square is over half a ton, which is why bag counts shock first time builders.
The tool above turns box size into volume, bags, and weight. The default needs 16.7 ft3, or 34 bags of 50 lb, weighing 1,667 lb. The metric match is 1.5 by 1.5 m at 20 cm for 0.45 m3 and 36 bags of 20 kg.
Depth sets the feel. Six inches suits toddlers and small toys, 8 to 10 in suits trucks and molds, and deeper fills spill over rails.
Play sand is the buy. Washed and screened play grades stay soft and drain, while mason sand packs like concrete and fill dirt stains.
Weight plans the haul. Half ton loads need a trailer or delivery plus a tarp crew, not a trunk of bags.
How to use
- Pick imperial (ft, in) or metric (m, cm).
- Enter inside length and width.
- Enter sand depth: 8 in or 20 cm suits many boxes.
- Read volume first.
- Read bag count next.
- Read weight and plan the haul.
Formula
- L
- Inside box length.
- W
- Inside box width.
- depth
- Sand depth.
Metric uses meters with m3, 20 kg bags at 0.0125 m3 each, and 1600 kg per m3. A 50 lb bag matches 0.5 ft3 each way.
Worked example
Example: 5 by 5 ft, 8 in deep
Imperial defaults: 5 by 5 ft at 8 in deep. These are also the default values, so the page opens on this answer.
- Box: 5 by 5 ft, 8 in deep.
- Feet: 8 / 12 = 0.6667 ft.
- Volume: 5 x 5 x 0.6667 = 16.7 ft3.
- Bags: ceil(16.7 / 0.5) = 34 bags (50 lb).
- Weight: 16.7 x 100 = 1,667 lb.
- Tool shows 16.7 ft3, 34 bags (50 lb), 1,667 lb.
Reference table
| Box | Volume | Bags |
|---|---|---|
| 4 by 4 ft, 6 in | 8 ft3 | 16 bags (50 lb) |
| 5 by 5 ft, 8 in | 16.7 ft3 | 34 bags (50 lb) |
| 6 by 6 ft, 8 in | 24 ft3 | 48 bags (50 lb) |
| 1.5 by 1.5 m, 20 cm | 0.45 m3 | 36 bags (20 kg) |
Limits
- Volume math only. Play safety needs standards.
- Assumes level fill. Mounded play needs more.
- Wet sand weighs more than the dry math.
- Delivery minimums may beat bag counts.
Common mistakes
- Buying fill dirt instead of play sand.
- Skipping fabric, then weeding the box.
- No lid, then hosting the block cats.
- Filling past rails so rain carries sand out.
- Hauling a ton in a sedan trunk.
Try it yourself
Quick checks. Answers sit tucked under each question.
4 by 4 ft at 6 in?
4 x 4 x 6/12 = 8 ft3. Bags are ceil(8 / 0.5) = 16 bags. Weight is 8 x 100 = 800 lb.
2 by 2 m at 30 cm?
Volume is 2 x 2 x 0.30 = 1.2 m3. Bags are ceil(1.2 / 0.0125) = 96 bags. Weight is 1.2 x 1600 = 1,920 kg.
Questions
How much sand volume?
Multiply length by width by depth in feet. Here 5 x 5 x 8/12 = 16.7 ft3.
How many bags?
Divide volume by 0.5. Here ceil(16.7 / 0.5) = 34 bags of 50 lb.
How heavy is that?
Multiply volume by 100 lb. Here 16.7 x 100 = 1,667 lb.
Which sand?
Washed play sand rated for boxes. Mason and fill sands pack hard and stain.
Fabric and lid?
Landscape fabric below, a lid above. Both cut weeds, cats, and rain crust.
Does this certify safety?
No. Fall height and entrapment need play standards beyond sand math.