Flooring calculator
A 12 × 11 ft bedroom with a 6 × 3 ft closet is 150 sq ft. With 10% for waste that is 165 sq ft, or 9 boxes at 20 sq ft per box. Add your rooms and the square feet printed on your carton.
Waste and boxes
10% is a common starting allowance for a straight plank layout. Diagonal and patterned layouts, stairs and rooms with many corners need more. 20 sq ft per box is only an example: read the carton.
How the boxes are counted
- Floor areaLength × width for each room, added up: 12 × 11 + 6 × 3 = 150 sq ft. Measure into doorways where the new floor will run.
- Add wasteMultiply by 1 plus the allowance for end cuts, defects and mistakes: 150 × 1.10 = 165 sq ft.
- Round up to boxesDivide by the coverage per box and round up: 165 ÷ 20 = 8.25, so 9 boxes, which hold 180 sq ft.
Bruce, a hardwood brand of AHF Products, calls 10% "the usual starting point for a straightforward plank layout" and says diagonal installs, busy patterns, stairs and irregular rooms need more. Mannington says a waste factor of 5 to 15% is added to a flooring order, depending on the product. Your installer or the product's own installation guide may give a different figure; type it in.
Sources: Bruce, How to Buy Flooring; Mannington, What to Expect From Your Floor Installation.
Boxes for common rooms
10% waste, at 20 sq ft per box as an example.
| Room | Floor area | With 10% waste | Boxes |
|---|---|---|---|
| 10 × 10 ft | 100 sq ft | 110 sq ft | 6 |
| 10 × 12 ft | 120 sq ft | 132 sq ft | 7 |
| 12 × 12 ft | 144 sq ft | 158.4 sq ft | 8 |
| 12 × 15 ft | 180 sq ft | 198 sq ft | 10 |
| 14 × 16 ft | 224 sq ft | 246.4 sq ft | 13 |
| 15 × 20 ft | 300 sq ft | 330 sq ft | 17 |
Questions people ask
- How much extra flooring should I buy?
- Start with 10% for a straight plank layout. Bruce calls that the usual starting point and says diagonal and patterned layouts, stairs and irregular rooms need more; Mannington gives a range of 5 to 15% depending on the product.
- How many boxes of flooring do I need for 500 sq ft?
- With 10% waste you need 550 sq ft. At 20 sq ft per box that is 27.5, so 28 boxes. Change the coverage per box to match your carton.
- Do I include closets?
- Yes, if the new floor runs into them. Add each closet as its own room so the list shows it.
- Should I keep leftover boxes?
- Keeping a few spare planks or tiles from the same order makes it easier to replace a damaged piece later. The list shows how many square feet are left over after waste.