Tinker 
How to use the flooring calculator
Choose feet or metres, then measure the room wall to wall and enter the length and width. Add a waste allowance, type in the coverage printed on one box of your chosen flooring, and optionally the price per square foot or square metre.
For L-shaped or irregular rooms, split the floor into rectangles, run each one separately and add the boxes together, or add the areas first and work out boxes once for a slightly smaller total. Closets and doorway thresholds count as floor, so include them.
The formula
Floor area is length × width. The area to buy is that area multiplied by (1 + waste % ÷ 100). Boxes needed is the area to buy divided by the coverage per box, always rounded up, because shops only sell whole boxes. The cost is the number of boxes × coverage per box × price per unit area, since you pay for everything in every box you buy, not only what goes on the floor.
The calculator also converts your room area to the other unit using 1 m² = 10.7639 ft², which helps when product coverage is listed in a different unit.
Worked example
A bedroom measures 15 ft × 12 ft, so the floor area is 180 ft² (16.72 m²). Adding 10% waste gives 198 ft². Laminate boxes cover 20 ft² each, so 198 ÷ 20 = 9.9, which rounds up to 10 boxes. Those 10 boxes cover 200 ft², and at $3.50 per ft² the flooring costs $700.
In metric: a 4 m × 3.5 m room is 14 m². With 10% waste that is 15.4 m², and boxes covering 2.2 m² give exactly 7 boxes. At 25 per m² the cost is 385.
Practical tips
Use about 5–10% waste for straight planks in a simple rectangular room, 10–15% for rooms with many corners, and 15–20% for diagonal, herringbone or large-format tile layouts. Buy all boxes from the same batch or dye lot so colour matches, and keep one spare box for future repairs.
The result is an estimate of flooring material only. Underlay, trims, transition strips, adhesive and installation labour are extra. Check the exact coverage on the box, because two products with the same plank size can pack different amounts.
Frequently asked questions
How much extra flooring should I buy?
Most installers recommend 10% extra for a standard straight lay. Go up to 15% for awkward rooms or diagonal layouts and around 20% for herringbone or patterned tile.
How do I calculate square footage of a room?
Multiply the length by the width in feet. A 12 ft × 14 ft room is 168 ft². For metric, multiply metres by metres to get square metres.
Why does the calculator round boxes up?
Flooring is sold in whole boxes, so 9.1 boxes still means buying 10. Rounding down would leave you short partway through the job.
Does the cost include underlay and installation?
No. The cost is boxes bought × coverage × your price per unit area. Add underlay, trims, adhesive and labour separately.