The formula
- 1. Length × width of each area, in feet. Add the areas together. Closets count.
- 2. Add 10% for cuts and waste (12–15% if you're laying diagonal or herringbone, or the room has many corners).
- 3. Divide by the box's coverage (it's on every product page), and round UP to whole boxes. Nobody sells you 3.4 boxes.
Worked example
Basement rec room 18' × 22' = 396 sq ft. Plus 10% = 436 sq ft. Box covers 23.8 sq ft → 436 ÷ 23.8 = 18.3 → 19 boxes. That's the number — not 18, and not “we'll come back for one more,” because the next batch can be a different dye lot.
Why you keep the spares
The offcuts and the part-box left over are your repair kit. One plank replaced from the same lot is invisible; one plank from a new lot is a stripe you'll see forever. Store flat, in the house, forever.
Let the site do it
Every flooring page here has a room calculator — length × width, the 10% toggle, and it rounds up to whole boxes automatically. The number in the cart is exactly what the counter would sell you: pick a floor and try it →