How to measure a room for flooring
Measure the length and width of the room at the widest points, wall to wall, and round up to the next half foot. Do not subtract the space under kitchen islands or built-in cabinets unless the flooring will not go there.
For an L-shaped room, split it into two rectangles. Enter the larger one as the length and width, and work out the smaller one by multiplying its length by its width. Put that number in extra area. Use the same field for closets and short hallways.
How the calculation works
Floor area = length × width + extra area
Area to buy = floor area × (1 + waste %)
Boxes = area to buy ÷ square feet per box, rounded up
In the example above, a 12 × 15 ft room is 180 square feet. Adding 10% for cuts brings it to 198 square feet. With 20 square feet in each box you need 10 boxes, which gives you 200 square feet of flooring.
How much extra flooring should you buy?
Every row ends with a cut piece, and some of those pieces are too short to start the next row. Mistakes and damaged planks add to that. The usual allowances are:
| Layout | Extra to add |
|---|---|
| Simple rectangle, planks laid straight | 5 to 10% |
| Room with closets, corners or a fireplace | 10% |
| Diagonal layout or herringbone | 15% or more |
| Large-format tile or complex patterns | 15 to 20% |
Flooring is sold by the box, so the amount you buy is always rounded up to whole boxes. If the result is only just over a full box, it is still worth buying the extra box.
Tips before you buy
- Keep one unopened box after the job. If a plank or tile is damaged years later, you will have an exact match, which can be impossible to find once a product is discontinued.
- Check that every box has the same lot or batch number, especially for tile and hardwood, where color can vary between production runs.
- You need the same square footage of underlayment as flooring, unless your flooring has a pad already attached.
- Wood and laminate often need to sit in the room for a day or two before installation. Follow the manufacturer's instructions on the box.
Frequently asked questions
How many boxes of flooring do I need for a 12 × 12 room?
A 12 × 12 ft room is 144 square feet. With 10% extra you need 158.4 square feet. With boxes that cover 20 square feet each, that is 8 boxes.
Do I need to buy 10% extra flooring?
For most rooms with a straight layout, yes. It covers the cut ends of each row and a few mistakes. A perfectly square room with few obstacles can get away with 5 to 7%, while herringbone and diagonal layouts need 15% or more.
How do I measure a room with angled walls?
Measure the room as if it were a full rectangle using the longest length and the widest width. The extra floor you include works as part of your waste allowance, so you can choose a lower waste percentage.
Does this work for tile and carpet?
It works for tile, laminate, vinyl plank and hardwood, which are all sold by the box. Carpet is usually sold off a roll in fixed widths, so the amount depends on where the seams go. Ask your carpet supplier to measure.
This calculator gives an estimate for buying materials. Your installer may recommend a different waste allowance for your room and product.