Flooring Calculator
Enter the length and width of each room, or one total area, to see how much flooring to buy. Add a waste allowance, the coverage printed on the box and a price, and the calculator rounds up to whole boxes and totals the cost.
Last updated November 4, 2026
10% is a common starting point; check your layout.
Printed on the box. Leave blank to skip boxes.
Leave blank to skip the cost.
Result
Buy 132 sq ft
| Measure | Value |
|---|---|
| Floor area | 120 sq ft |
| With 10% waste | 132 sq ft (12.26 m²) |
Area method: it adds a waste percentage and does not draw the layout. Check the quantity with your supplier.
Show the work
Formula: area to buy = sum of (length x width) x (1 + waste / 100); boxes = ceil(area to buy / box coverage)
- Area: room 1 12 x 10 = 120; total 120 sq ft.
- Waste: 120 x (1 + 10 / 100) = 132 sq ft.
- Purchase: 132 sq ft rounded up to a whole unit = 132 sq ft.
Result: Buy 132 sq ft
How the flooring amount is worked out
area to buy = Σ(length × width) × (1 + waste ÷ 100)
boxes = ceil( area to buy ÷ box coverage )
Each room is a rectangle, so its area is length times width. The areas are added, a waste allowance is applied on top, and the result is divided by the area in one box and rounded up. Flooring is sold in whole boxes, so you always buy a little more than the allowance.
Two rooms of 12 ft by 10 ft and 10 ft by 8 ft add up to 120 + 80 = 200 sq ft. With 10 percent waste that is 220 sq ft, and boxes of 20 sq ft make exactly 11 boxes. At $3.50 per square foot the cost is 220 × $3.50 = $770.
See how we calculate for the formulas, sources and review schedule behind every calculator.
Choosing a waste allowance
The calculator starts at 10 percent, a common allowance for a straight layout. Diagonal patterns and rooms with many corners create more offcuts, so many installers allow more. Treat any figure as a starting point and confirm it with your supplier or installer.
Pricing by area or by box
Enter the price either per square foot (or square meter) or per box. Priced by area, the cost covers the full boxes you buy; priced by box, it is the box count times the price. Pricing by box needs the box coverage.
How to use the Flooring Calculator
- Choose imperial or metric, then measure by rooms or by one total area.
- Enter each room’s length and width, or the total area.
- Set the waste percentage and, if you know it, the coverage of one box.
- Add a price per square foot, square meter or box to see the cost.
- Read the boxes to buy, then use Copy, Print or Share.
Worked example
Two rooms of 12 ft by 10 ft and 10 ft by 8 ft total 200 sq ft. Adding 10 percent waste gives 220 sq ft, so boxes of 20 sq ft make 11 boxes with no spare box. At $3.50 per square foot the cost is $770.
| Floor area | With waste | Boxes |
|---|---|---|
| 120 sq ft | 132 sq ft | 7 |
| 200 sq ft | 220 sq ft | 11 |
| 300 sq ft | 330 sq ft | 17 |
| 500 sq ft | 550 sq ft | 28 |
Frequently asked questions
How much extra flooring should I buy?
Ten percent is a common starting point for a straight layout, and diagonal layouts often need more. Treat it as a rule of thumb and ask your installer.
How do I measure a room that is not a rectangle?
Split it into rectangles and enter each as a room, up to six, or work out the total area yourself and use the one total area option.
Why does the result show boxes as well as area?
Flooring is sold in whole boxes, so the calculator rounds up to the next full box. The difference is the spare flooring you keep for repairs.
Does this work for tile, laminate or vinyl?
It uses plain area and box coverage, so it fits any flooring sold by the box. For tile with grout joints, the Tile Calculator counts individual tiles.