How to use the flooring calculator
- Enter the room length and width.
- Choose a waste allowance. Around 10% is a common starting point for a straight lay; diagonal and herringbone layouts cut more boards, so allow more.
- Enter the coverage per box from the product label.
Buy all the boxes at once, from one production lot if you can, so shades match between rooms, a tip Decoratoradvice gives for every flooring job.
Flooring formula
Floor area = length × width
Area with waste = floor area × (1 + waste)
Boxes = area with waste ÷ coverage per box, rounded up
Worked example
A 15 × 12 ft bedroom, 10% waste, boxes covering 20 sq ft:
15 × 12 = 180 sq ft
180 × 1.10 = 198 sq ft
198 ÷ 20 = 9.9, so 10 boxes
Rooms that are not rectangles
Split the floor into rectangles, find each area with the square footage calculator, and add them. Then enter the total as length × 1 (for example, 204 × 1) with your waste allowance. Closets, alcoves and the floor under door openings all count.
Before you buy
- Check the subfloor. Flooring over an uneven or damaged subfloor can gap or bounce; replace damaged panels with the help of the plywood calculator.
- Buy all boxes from one production lot so colour and gloss match. The lot number is printed on the box.
- Keep a spare box for future repairs.
- Plan the trim at the same time: the baseboard calculator counts pieces for the room's perimeter.
Choosing between flooring types
| Floor type | How it is sold | Calculator | |
|---|---|---|---|
| Laminate, vinyl plank, engineered wood | Boxes by square foot | This one | |
| Ceramic or porcelain tile | Tiles or boxes | [[tile | Tile calculator]] |
| Carpet | Roll width × length, by square yard | [[carpet | Carpet calculator]] |
Common mistakes
- No waste allowance. End cuts and boards with damaged tongues add up.
- Rounding boxes down. 9.9 boxes means 10.
- Measuring around fixed cabinets twice. Measure only the floor you will cover.
Frequently asked questions
How much extra flooring should I buy?
Around 10% for a straight lay in a rectangular room is a common allowance. Rooms with many corners, diagonal layouts and herringbone patterns need more.
How many boxes of flooring do I need for 500 sq ft?
With 10% waste, 550 sq ft. Divide by the coverage on your box: at 20 sq ft per box, 27.5, so 28 boxes.
Do I include closets?
Yes, if the flooring runs into them. Add their area to the room.
Should I subtract the area under kitchen islands?
If the flooring will not go under the island, subtract its footprint. Floating floors usually stop around fixed cabinets.
What is the difference between this and the tile calculator?
Plank and laminate flooring is sold by area per box. Tile is counted piece by piece, including grout joints; use the tile calculator.
How do I measure a room for flooring?
Measure wall to wall at the longest and widest points, to the nearest inch, and convert inches to decimal feet.
Key takeaways
- Boxes = floor area × (1 + waste) ÷ coverage per box.
- Start around 10% waste; add more for diagonal layouts and awkward rooms.
- Buy all boxes from one lot and keep a spare.
- Check the subfloor before you lay the new floor.