How it works
The calculator finds the floor area, adds your waste allowance, and divides by the area one box covers.
Area = Length × Width
Area with waste = Area × (1 + Waste ÷ 100)
Boxes = ⌈ Area with waste ÷ Coverage per box ⌉
Area you buy = Boxes × Coverage per box
⌈ ⌉ means rounding up to the next whole number: you can’t buy part of a box. Rounding happens only at the end, so small fractions are not lost along the way.
Room dimensions and box coverage are converted to one internal unit before dividing, so you can measure the room in feet and inches and still enter the coverage in square feet or square yards.
Worked example
Inputs
- Measure by
- Known floor area
- Floor area
- 200 sq ft
- Coverage per box
- 20 sq ft
- Waste allowance
- 10 %
Result
- Floor area
- 200 sq ft
- Area incl. waste
- 220 sq ft
- Boxes
- 11
- Area you buy
- 220 sq ft
Common mistakes
- Measuring only the open floor and forgetting closets, alcoves and the space under door openings where the flooring continues.
- Typing the box’s plank count instead of its coverage. This calculator needs the area one box covers, which is printed on the carton.
- Leaving the waste allowance at 0. The last plank in every row is cut, and those offcuts can’t always start the next row.
- Buying boxes from different production lots. Color and finish can vary between lots, so buy everything at once and check the lot number.
Assumptions and limits
- The room is a rectangle, or you have entered its total floor area.
- The count is an area estimate. It does not plan individual rows or cuts, so rooms with many corners, angled walls or diagonal layouts may need a larger waste allowance.
- Boxes are rounded up to whole boxes. Without a coverage per box, only the area is shown.
- Underlayment, transition strips and baseboard or quarter-round are not included.
Frequently asked questions
How much extra laminate should I buy?
It depends on the room shape, the plank length and the layout. Check the manufacturer’s installation instructions and ask your retailer; straight layouts in simple rectangular rooms need the least, diagonal layouts and rooms with many corners the most. Many people also keep a spare box for future repairs.
Why is the “area you buy” larger than the area incl. waste?
Laminate is only sold in whole boxes. The calculator rounds up to the next full box, so the area you actually buy is the number of boxes times the coverage per box, which is usually a little more than you need.
Do I need to subtract kitchen islands or built-in cabinets?
If the flooring will not go under them, yes. Measure their footprint, subtract it from the room area, and enter the result with the “known floor area” option. The installation instructions say whether the floor may be installed under fixed cabinets.
Sources
- NIST Handbook 44, Appendix C – General Tables of Units of Measurement — National Institute of Standards and Technology. Exact unit definitions: 1 in = 2.54 cm, 1 yd³ = 27 ft³, 1 US gal = 231 in³, 1 lb = 0.45359237 kg.
Method reviewed November 2, 2026