How much extra flooring should I buy?

Five to eight percent for a straight layout in a rectangular room, 12–15 % for diagonal patterns, herringbone or rooms with many angles. Keep a spare box for repairs.

How many boxes of flooring do I need?

Square feet to buy ÷ the coverage printed on the box, rounded up. Coverage differs by product, so check the label and type it in.

Do I need underlayment?

Floating laminate and vinyl plank usually need a thin underlayment unless it is attached to the plank; glue-down and nail-down floors have their own requirements. The line can be ignored if you do not need it.

Flooring calculator

Form 64 · Materials estimateFigures checked 2026-09-04

US customary

Measurements

Length(ft)

Width(ft)

Areas this size

What you need

Quantity · Amount

01Area to cover30 × 20 ft600 sq ft
02Flooring to buyincluding 8 % waste648 sq ft
03Boxs at 20 sq ft each$4 per sq ft33 boxes$2,268
04Underlayment, 100 sq ft rolls$30 per roll7 rolls$210

Total, materials$2,478

The material

Waste allowance(%)Straight rooms 5–8 %; diagonal layouts and many cuts 12–15 %

Coverage per box(sq ft)Printed on the box: laminate ≈ 20 sq ft, vinyl plank 18–24, hardwood 20–25

Prices — put in what you were quoted

Underlayment price($ per roll)100 sq ft rolls; skip if the planks have it attached

Price($ per sq ft)Laminate $1–3 per sq ft, vinyl plank $2–5, hardwood $4–10

Total, materials648 sq ft of flooring$2,478

Where these figures come from

Box coverage is product-specific; the default 20 sq ft is a common laminate carton.
Underlayment rolls of 100 sq ft: the common size.
Prices are typical US retail figures at the date on this sheet.

Type the room's length and width (add closets as extra areas). Flooring is sold by the box; the coverage per box is printed on the label, usually 15–25 sq ft. The sheet adds an 8 % cutting allowance, rounds up to whole boxes and adds underlayment rolls of 100 sq ft.

Worked examples

Living room 14 × 18 ft: 14 boxes — boxs at 20 sq ft each, about $1,043 in materials.
Three bedrooms 12 × 12 ft: 24 boxes — boxs at 20 sq ft each, about $1,783 in materials.

How it is worked out

Area × (1 + waste) = flooring to buy. Boxes = that ÷ square feet per box, rounded up. Cost = square feet to buy × price per square foot, plus underlayment rolls × roll price.

The figures behind it

Box coverage is product-specific; the default 20 sq ft is a common laminate carton.
Underlayment rolls of 100 sq ft: the common size.
Prices are typical US retail figures at the date on this sheet.

Every figure here is an estimate. Materials vary with moisture, compaction and product; order a little extra and confirm quantities with your supplier.

Questions people ask

How much extra flooring should I buy?: Five to eight percent for a straight layout in a rectangular room, 12–15 % for diagonal patterns, herringbone or rooms with many angles. Keep a spare box for repairs.
How many boxes of flooring do I need?: Square feet to buy ÷ the coverage printed on the box, rounded up. Coverage differs by product, so check the label and type it in.
Do I need underlayment?: Floating laminate and vinyl plank usually need a thin underlayment unless it is attached to the plank; glue-down and nail-down floors have their own requirements. The line can be ignored if you do not need it.

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