The formula
Boxes needed = (total sq ft × (1 + waste%)) ÷ sq ft per box, rounded up.
Example: 200 sq ft room, 10% waste, 22 sq ft per box → 220 ÷ 22 = 10 boxes exactly. At 205 sq ft with same box size you still need 11 boxes after rounding.
Where to find sq ft per box
- Printed on the carton front — "Coverage: 20.06 sq ft"
- Retailer listing under specifications
- Tile: pieces per box × (tile length × width ÷ 144)
- Never assume — box sizes vary even within the same brand line
Store pickup checklist
Combine rooms in the box count calculator only when every room uses the identical product code.
- Screenshot the SKU and sq ft per box from the product page
- Confirm batch/lot color if buying over multiple weeks
- Add one box for attic storage — match dye lot on receipt
- Buy underlay and transitions in same trip when possible