Flooring Calculator

A flooring calculator turns your room size into the number of boxes to buy — plus the underlayment that goes beneath — with extra added for cuts and the odd damaged plank. Measure the room, set your product's box coverage, and it does the rest.

Your measurements

Result

Flooring is sold by the box, and the coverage printed on the box is what matters, not the plank size. We add a waste allowance (more for diagonal or herringbone layouts), and you should always buy a spare box from the same lot for future repairs.

How it is calculated

Boxes = floor area divided by the coverage per box, times one plus the waste percentage, rounded up. Underlayment is bought to match the floor area. Waste rises with diagonal and patterned layouts and with lots of small cuts around cabinets and doorways.

Steps

Choose room length × width, or enter total area.
Enter the measurements in feet (or metres).
Set the coverage per box from the product label — around 20 sq ft is common.
Set a waste allowance: 10% for a straight lay, 15%+ for diagonal or herringbone.
Read the box count and add one spare from the same lot.

Worked example

A 15 × 12 ft room is 180 sq ft. With 20 sq ft boxes and 10% waste, you need 10 boxes — plus about 180 sq ft of underlayment.

Common questions

How many boxes of flooring do I need?

Divide your floor area by the box coverage and add 10% (more for diagonal layouts). The calculator rounds up and adds underlayment.

Why buy a spare box?

Dye lots vary between production runs, so a spare from the same lot guarantees a match for future repairs.

Do I need underlayment?

Most floating floors (laminate, vinyl) need underlayment for sound and moisture; glue-down and nail-down floors differ — see the specific calculators.

How much waste should I allow?

10% for a straight lay, 15% for diagonal, up to 20% for herringbone or rooms with many cuts.