Flooring Needed Calculator

Ordering flooring is an arithmetic problem with a rounding trap at the end, because you cannot buy a fraction of a box.

Room lengthMeasured along the longest wall, in feet.Room widthMeasured across the room, in feet.Coverage per packSquare feet a single box covers. Printed on the box.Waste allowance(%)Ten for a plain room, fifteen for diagonal patterns, twenty for awkward corners.Price per packCost of one box, used only for the total.

Boxes to order

Area with waste: 198
Total cost: $420.00
Waste allowance area: 18

Values update as you type. This calculator covers the single scenario its formula assumes — see Common Mistakes for what it leaves out.

The formula this calculator uses

boxes = (room area x (1 + waste allowance)) / pack coverage

A: Floor area to cover, in square feet
W: Waste allowance, as a decimal fraction
C: Coverage per pack, in square feet

How to check the result by hand

1
Measure the room and split awkward shapes
Length times width for a rectangle. For L-shapes, add the two rectangles together. Include closets, alcoves and landings at this point rather than later.
2
Choose a waste allowance
Ten percent for a plain rectangular room, fifteen for diagonal layouts, twenty or more for rooms with many corners. The allowance is a decimal, so ten percent is 0.10.
3
Inflate the area
Fifteen by twelve is 180 square feet. Times 1.10 gives 198 square feet of material to buy, which is the number the rest of the calculation works from.
4
Divide by pack coverage
198 divided by 20 is 9.9 boxes. This decimal is where most people go wrong, because nine boxes visibly covers the floor and ten boxes does not obviously get used.
5
Round up and add spares
Ten boxes is the order quantity. Buy one or two extra full boxes, unopened, because dye lots differ between production runs and a later repair needs matching material.

For worked examples, common mistakes and the limits of this formula, read the full How To Calculate Flooring Needed page.