Flooring is sold by the box, and each box states how many square meters or square feet it covers. A 5 × 4 m room is 20 m²; with 8% extra for cuts that is 21.6 m², or 10 boxes of 2.2 m². Type the room size, choose the layout, enter the area printed on the box and the calculator gives the boxes to buy, what is left over, the underlayment, the baseboard length and the cost.
Boxes for common rooms
Metric, 2.2 m² per box:
| Room | Area | Straight (+8%) | Diagonal (+12%) | Herringbone (+15%) |
|---|---|---|---|---|
| 3 × 3 m | 9 m² | 5 | 5 | 5 |
| 4 × 3 m | 12 m² | 6 | 7 | 7 |
| 5 × 4 m | 20 m² | 10 | 11 | 11 |
| 6 × 5 m | 30 m² | 15 | 16 | 16 |
| 8 × 6 m | 48 m² | 24 | 25 | 26 |
US units, 24 ft² per box:
| Room | Area | Straight (+8%) | Diagonal (+12%) | Herringbone (+15%) |
|---|---|---|---|---|
| 10 × 10 ft | 100 ft² | 5 | 5 | 5 |
| 12 × 12 ft | 144 ft² | 7 | 7 | 7 |
| 14 × 12 ft | 168 ft² | 8 | 8 | 9 |
| 16 × 13 ft | 208 ft² | 10 | 10 | 10 |
| 20 × 15 ft | 300 ft² | 14 | 14 | 15 |
Because boxes are whole, the rounding often swallows the difference between layouts in small rooms; in big rooms, the extra for a diagonal or herringbone floor adds real boxes.
Rooms that are not rectangles
Split an L-shaped room into two rectangles, run the calculator for each and add the areas; or use the area calculator for odd shapes. Add closets and the floor under doors to the next room, and lay the boards in the direction of the longest wall or the main light.
Before you lay it
Let the boards acclimatize in the room as the maker says, often about 48 hours. Check that the subfloor is flat; deep dips need a leveling compound, which the floor screed calculator can count. Leave the expansion gap the instructions ask for at the walls: the baseboard covers it.
The calculator works offline once saved, so you can use it in the store aisle.
Frequently asked questions
How do I calculate how much flooring I need?
Multiply the room's length by its width, add the extra for cuts and divide by the area in one box, rounding up. A 5 × 4 m room is 20 m²; with 8% extra, 21.6 m², so 10 boxes of 2.2 m².
How much extra flooring should I buy?
Around 5% for a simple rectangular room laid straight, 8–10% for an ordinary room, 12% or more for a diagonal layout or a room with many corners and doorways, and about 15% for herringbone or chevron.
How many boxes for a 12 × 12 ft room?
144 ft². With 24 ft² per box and 8% extra, 155.5 ft², so 7 boxes.
Do I need to buy underlayment?
Most floating laminate and many vinyl floors need an underlayment unless it is already attached to the boards. Buy it for the floor area; rolls are usually overlapped or taped as the maker says.
Should I keep spare boxes?
Keeping one spare box is wise: a later repair with boards from a different batch may not match in color.
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