Flooring calculator
Square footage plus the number of boxes to buy, with the waste factor built in.
Calculator
Detailed breakdown
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How to use this calculator
Measure
Measure the room in feet. For L-shaped rooms, split into rectangles and add the results.
Calculate
Once you hit calculate, results update as you type. Change any number to compare options instantly.
Order
Print the estimate and take it to your supplier. Quantities are rounded up so you don't come up short.
Why the waste factor decides whether you finish the job
Room area is the easy half: length times width. The part that determines whether you finish the installation is the waste factor — the extra material consumed by cuts, defective boards and the cutoffs that end up too short to use.
Ten percent is the working default for a straightforward rectangular room laid in straight rows. Go to 15 percent for diagonal layouts, which produce far more angled cutoffs, and 20 percent for herringbone or chevron, or for rooms with closets, alcoves and multiple doorways.
A 12 by 15 room is 180 square feet. At 10 percent waste you need 198 square feet, which in 20-square-foot boxes means 10 boxes. Note that you have to buy whole boxes — the calculator rounds up because suppliers do not sell partial boxes.
Two habits worth adopting. First, buy one extra box beyond the calculation and store it: flooring is manufactured in dye lots, and a plank replaced three years later from new stock will not match. Second, check whether your supplier accepts returns on unopened boxes, which makes over-ordering nearly free.
Frequently asked questions
How much extra flooring should I buy?
Ten percent for straight layouts, 15 for diagonal, 20 for herringbone or complex rooms. Plus one spare box stored for future repairs.
How do I measure an L-shaped room?
Split it into rectangles, calculate each separately, and add the totals. Measure at the widest points and include closets you plan to floor.
How many boxes of flooring do I need?
Divide your total square footage including waste by the coverage per box, then round up. Coverage is printed on every box and varies by product.
Do I include closets and doorways?
Include closets if you are flooring them. Add a little for doorway transitions, which often need a full plank cut down.
Why does dye lot matter?
Flooring color varies slightly between production batches. Buying all your material at once, plus a spare box, avoids a visible mismatch on future repairs.
Sources
Formulas and material assumptions on this page follow published industry guidance: