How to calculate flooring boxes
Measure each room in feet and multiply length × width; add closets and alcoves separately. Multiply the total by 1.10 for a 10% waste allowance, divide by the coverage printed on the box (for example 22.5 sq ft) and round up to a whole box.
Worked example: a 12 × 15 ft living room
The room is 180 sq ft. With 10% waste that is 198 sq ft. At 22.5 sq ft per box you need 198 ÷ 22.5 = 8.8, so 9 boxes. You will buy 202.5 sq ft and have about 22.5 sq ft left over after installation. At $45 per box the flooring costs $405.
How much waste to allow
10% is standard for rectangular rooms with the planks laid straight. Use 15% for rooms with many corners, closets or hallways and for diagonal layouts, because more planks are cut. Keep one unopened box for future repairs — the same color and batch can be hard to find later.
Before you install
Check the manufacturer's instructions for acclimating the boxes in the room, the expansion gap to leave at walls and whether an underlayment is required. Underlayment is bought for the same floor area.