Measure the room, add a waste allowance for cuts, and find out how many boxes of flooring to order.
Room area is length times width. Installers add a waste allowance — typically 10% for straight-lay plank or laminate, 15% for diagonal layouts or rooms with many alcoves — to cover cuts, mistakes and spare boards for future repairs. Boxes are always rounded up because flooring is sold in whole boxes, and ordering from one batch avoids shade variation between production runs.
How much extra flooring should be ordered? Ten percent over the measured area is the standard allowance for a simple rectangular room laid straight. Use 15% for diagonal patterns, herringbone, stairs or awkward shapes.
Why keep spare boards after the job? A few leftover boards from the same batch make future damage repairs invisible. Flooring ranges are discontinued regularly, so matching replacements are often impossible later.