Flooring Calculator (Square Feet, Waste, Boxes and Cost)

Enter the room size or area, the layout and the coverage per box, and this flooring calculator gives the square feet to order, the boxes, the underlayment and the cost. The waste allowance follows the layout: 5% for a straight lay, 10% for rooms with closets and angles, 15% for diagonal, herringbone and chevron. Works in square feet or square metres.

Flooring calculator

How it works

Area = length × width (× rooms), or the area you measured
To order = area × (1 + waste)
Boxes = order ÷ coverage per box, rounded up; the boxes bought are what you pay for
Underlayment = area × 1.05 ÷ roll coverage, rounded up

Worked example

A 15 × 12 ft living room in laminate, straight lay, 20 sq ft per box, 100 sq ft rolls of underlayment:

Units: Feet and inches
Measure by: Length and width
Length: 15 ft
Width: 12 ft
Rooms this size: 1
Layout: Straight lay (5% waste)
Waste: 5%
Coverage per box: 20 sq ft
Price per square foot or m² (optional): $0
Underlayment roll coverage (0 to skip): 100 sq ft

The calculator gives:

Flooring to order: 189 sq ft (180 sq ft + 5% waste)
Boxes: 10 × 20 sq ft = 200 sq ft
Area: 180 sq ft (16.72 m², 20 sq yd)
Underlayment: 2 rolls at 100 sq ft

The room is 180 sq ft; with 5% waste, 189 sq ft, so 10 boxes (200 sq ft) and two rolls of underlayment. Laying the same planks on the diagonal takes 15% waste: 207 sq ft and 11 boxes.

Material and waste notes

Measure into doorways and closets. Irregular rooms: split them into rectangles and add, or use the square footage calculator.
The waste covers end cuts and defects; herringbone and chevron patterns waste more at the borders.
Keep a box of leftovers for repairs. Dye lots and embossing change between production runs.
Transitions, quarter round, stair nosing and adhesive are not included.
Solid hardwood is often sold by the square foot in bundles rather than boxes; enter the bundle coverage.

Frequently asked questions

How much extra flooring should I buy?

5 to 10% for straight layouts, 15% for diagonal, herringbone or chevron, and more for small rooms with many cuts. Round up to whole boxes.

How many boxes of flooring for a 12×12 room?

144 sq ft with 10% waste is 158 sq ft, so 8 boxes of 20 sq ft.

How do I calculate square footage for flooring?

Multiply the room’s length by its width in feet. Break odd shapes into rectangles and add them; then add the waste allowance.

Does the flooring calculator include underlayment?

Yes, as rolls at the coverage you enter (commonly 100 sq ft). Some laminate and vinyl planks have it attached; set the roll coverage to 0 to skip it.

How many square feet in a box of laminate?

Usually 18 to 24 sq ft; hardwood about 20 sq ft; luxury vinyl plank 20 to 30. It is printed on the carton.

Sources

NIST Special Publication 811, Guide for the Use of the International System of Units (unit conversion factors)

Last reviewed: 26 September 2026. The calculation is covered by automated tests with known answers taken from the sources above. Found an error? Please let us know.