How to use this calculator
- Measure the length and width of the room in feet. For an L-shaped room, calculate each rectangle and add them using the extra area box.
- Enter any extra area, such as a closet or hallway that gets the same flooring.
- Pick the layout. Straight lays waste the least, while diagonal and herringbone patterns waste the most.
- Enter the coverage per box from the product label.
- Add a price per square foot to see the cost of the boxes you will buy.
How the numbers are calculated
Floor area is length multiplied by width plus any extra area. The waste percentage is added to cover cuts, mistakes and boards with defects. The result is divided by the coverage of one box and rounded up, because boxes are sold whole.
The cost uses the full area of the boxes you buy, not just the room, because you pay for every box.
Worked example
A room 15 ft by 12 ft is 180 sq ft. Adding a 20 sq ft closet gives 200 sq ft. With 10% extra you need 220 sq ft. At 20 sq ft per box that is exactly 11 boxes. At $3.50 per square foot the boxes cost $770.
Tips before you buy
- Buy all your boxes at the same time so the color and pattern come from the same production lot.
- Keep one or two spare boxes. A matching board is hard to find years later.
- Do not measure under fixed cabinets. Flooring is normally not installed there, but include areas under appliances you may move.
- Many floors need to sit in the room for a few days before installation. Follow the manufacturer instructions.
- Ask whether the product needs underlayment, and add transitions and trim to your shopping list.
Frequently asked questions
How much extra flooring should I buy?
Ten percent is the usual figure. Use about 5% for a simple straight layout in a square room, and about 15% for diagonal or herringbone patterns, or tile with many cuts.
How do I measure an L-shaped room?
Split it into two rectangles, multiply length by width for each, and add the areas. Enter one rectangle in the length and width boxes and the other in the extra area box.
Do I include closets in the measurement?
Yes, if the same flooring will go inside them. Add their area using the extra area box.
Is the waste allowance different for tile?
Tile often needs 10 to 15% extra because of cuts and breakage, especially with large tiles or diagonal layouts.
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These results are estimates for planning purposes. Material sizes, densities and local requirements vary, so confirm quantities with your supplier or a qualified contractor before ordering.
Last updated October 11, 2026.