How Much Flooring Do I Need?

If you are asking how much flooring do i need, start with the floor itself, not the shop shelf. Flooring is sold by area and packed in boxes, so every sensible estimate follows the same chain: measure the room, add a waste allowance for cuts, then divide by the coverage printed on the box you are actually buying. Skip any step in that chain and you either run short near the last wall or pay for boxes you will store for years. Work through it once, carefully, and the answer is usually right to within one box. If you would rather skip the arithmetic, our flooring calculator does the same sums instantly and lets you change the room size, the waste and the box coverage until the result matches your room.

The direct answer

Measure the room’s area, add a waste allowance, then divide by the coverage printed on the box and round up to whole boxes. For a straightforward room laid straight, the waste allowance to start with is 10%. So the full method is: area, plus 10%, divided by box coverage, rounded up. You cannot buy part of a box, and that rounding up is not a fudge. It is how flooring is sold, and the spare it leaves is usually what covers the awkward cuts at the end of the job.

That 10% figure applies to a straight, parallel lay in a reasonably regular room. Diagonal layouts, herringbone and other patterns need more, because almost every edge piece is cut at an angle. If your plan involves a pattern, do not stretch the 10% and hope. Use the higher allowance for your pattern, as explained in our companion guide on flooring waste and the 10% rule, and then run the same area, waste and box calculation with the new percentage.

How to measure your room

Simple rectangles: length times width

For a simple rectangular room, measure the longest length and the widest width, in the same units, and multiply one by the other. A room that is 12 feet long and 14 feet wide has an area of 168 square feet. Measure wall to wall at floor level, not skirting to skirting guesswork, and check the room in two places if you can. Older rooms are rarely perfectly square, so if the width differs at each end, use the larger measurement for buying. Write each measurement down as you take it. A transposed number on paper is a far more common cause of a wrong order than any fault in the flooring itself.

L-shaped rooms: split them into two rectangles

Do not try to force an L shape into one length and one width, and do not measure the longest length by the longest width, because that counts a corner of floor that does not exist. Instead, split the shape into two rectangles, measure each one, and add the two areas together. For example, take a room with a main area of 16 by 12 feet and an alcove of 6 by 4 feet. The main area is 16 multiplied by 12, which is 192 square feet. The alcove is 6 multiplied by 4, which is 24 square feet. Added together, the room is 192 plus 24, which is 216 square feet. That 216 is the area you carry forward to the waste and box steps, not the larger, imaginary rectangle.

Measure in the units the boxes use. If the coverage on the carton is printed in square feet, measure and work in square feet. If it is printed in square metres, work in metres and m² from the start, rather than converting a finished total and rounding twice along the way. Include cupboards, wardrobes and any other floor the new surface will run into, and include the floor inside doorways you are flooring through. A doorway strip looks tiny until the last row reaches it and there is nothing left in the box to cover it. Our flooring calculator accepts up to three rooms or areas, which makes this split-and-add method easy to check.

Worked example: a 12 x 14 ft room

Take an ordinary rectangular room that measures 12 feet by 14 feet, laid straight. Step one is the area: 12 multiplied by 14 is 168 square feet. Step two is waste: add 10%, so 168 multiplied by 1.10 is 184.8 square feet, which most people would round in conversation to 185 square feet to buy. Step three is boxes. If the boxes you are buying each cover 20 square feet, divide 184.8 by 20, which gives 9.24. You cannot buy 9.24 boxes, so step four is to round up, always up, to 10 boxes. Those 10 boxes give you 200 square feet of coverage for a job that needs 184.8, leaving a modest spare for cuts and for the future.

Notice what the rounding did. It did not create a mountain of waste, and it did not change the method. It simply turned a decimal answer into the whole boxes a shop can actually sell you. If your calculation ever lands just above a whole number of boxes, that extra box is still the right purchase. Running short by a single plank near the door is more expensive, in time and in batch matching, than keeping one box too many.

How to read a box label

The number that matters most on the carton is the coverage per box, and it is the figure you should copy into your calculation. Do not borrow a coverage figure from a similar product, a website listing for a different range, or the box you bought for another room last year. Next, check the planks per box and the plank size. Planks per box tells you how the coverage is made up, and plank size helps you picture how cuts will fall and whether a short box might suit a small room better. Two products can look almost identical on display and still differ enough in coverage to change your box count by one or two boxes.

While you are reading the label, check the batch or production run information as well. Never mix production batches in one room if it can be avoided. Colour, finish and even the exact tone of a printed pattern can vary slightly between batches, and the difference that is invisible between two loose planks can show clearly once a whole floor is laid in daylight. Buy the whole room in one batch, in one order, and keep a note of the batch details with your receipt in case you ever need to match the floor later.

Underlayment, trims and other separate purchases

Underlayment and trims are separate purchases, and they should not be folded into your box count for the flooring itself. Underlayment, where your product needs it, is sold by the same area, so the same total applies: work out the area to buy, including your waste thinking, and order underlayment to cover that area rather than the bare room measurement alone. Some planks come with underlay already attached, so check your product before you buy a second layer you do not need. Trims, thresholds, beading and door bars are different again. They are sold by length or by the piece, so measure the walls, doorways and transitions they will cover and buy them on that basis.

Before you order, run the whole room through the flooring calculator one last time with the real box coverage from the carton in front of you, not a default you left in place. Check the area, check the waste percentage for your pattern, and check that the box count has been rounded up. That final two-minute check, done with the actual label to hand, catches almost every avoidable flooring order mistake.

Frequently asked questions