Measure & plan

Order enough product once. Measuring twice is cheaper than a second shipping fee for a discontinued color.

Measure each room — length × width in feet for square footage. Include closets that get the same floor.
Add 10–15% waste — closer to 10% for simple rectangles; closer to 15% for diagonals, many angles, or busy patterns.
Sum rooms separately — then apply waste to the total (or per phase if you’re buying in stages).
Doorways & transitions — measure openings for T-moldings and reducers; don’t double-count shared doorway floor area.
Pick plank direction — often parallel to the longest light source or main hallway sightline. Dry-layout a few rows if unsure.
Check last-row width — if the math leaves a skinny strip against the far wall, rip the first row narrower so both edges look balanced.

Walk through the full example and waste math on the Measure page — same method, with a worked bedroom + closet example.

Also worth planning

Extra boxes for future repairs (same dye lot if possible).
Undercut door jambs so planks slide under trim.
Appliance pulls and toilet flanges if bathrooms are in scope (advanced; many DIYers hire help here).