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Flooring Calculator

How many boxes of laminate, vinyl or hardwood a room needs.

Your measurementsEvery assumption editable01

Printed on the carton. Commonly 18–24 sq ft.

10% for a straight lay in a square room, 15% for diagonal, 20% for herringbone.

Boxes requiredCalculated live02

Result

16boxes

Buy 16 boxes

Floor area20 ft × 14 ft
280 sq ft
With waste allowance+10%
308 sq ft
Boxes requiredat 20 sq ft per box
16 boxes
Total supplied
320 sq ft
Left over
40 sq ft

Buy the whole job in one order. Batches are dye-lot matched, and a box bought later can be visibly off against the rest of the floor.

Keep at least a few spare planks after fitting. A damaged board years later is a single-plank repair if you have stock and a full refloor if you do not.

For an L-shaped or irregular room, split it into rectangles, calculate each separately and add the results before applying waste.

Enter the room dimensions and the coverage printed on the carton, then pick a waste allowance that matches your layout. Straight lay in a square room wastes little; herringbone in a room with alcoves wastes a great deal. The result is whole boxes, with the leftover figure shown so you know how much spare you are carrying.

Why use this tool?What it does differently03

Why use this tool?

Answers in boxes, not square feet

Flooring is sold by the carton, so square footage is an intermediate step rather than an answer. This converts it and rounds up.

Waste matched to the layout

Preset allowances for straight, diagonal and herringbone lays, because a chevron pattern genuinely wastes twice what a straight lay does.

Shows the leftover

How much spare the rounding leaves you. Under a few square feet is tight; you want some stock for future repairs.

Any carton size

Coverage per box varies from about 18 to 24 square feet between products. Enter what is on the one you are buying.

How this worksThe method04

How this flooring calculator works

Floor area is length times width. The waste allowance is then applied as a percentage uplift, and the result is divided by the coverage of a single carton and rounded up to the next whole box.

The waste percentage is doing the real work here. A straight lay in a rectangular room produces offcuts only at two edges, and the cut end of one row often starts the next — so ten per cent is generous. Diagonal and herringbone layouts cut every perimeter piece at an angle, and those offcuts are rarely reusable, which is why the allowance climbs to fifteen and twenty.

The total supplied and leftover figures exist because rounding up to whole boxes can land you anywhere from a few square feet to nearly a full box of spare. Knowing which you have got tells you whether to order an extra carton for future repairs.

How to use itStep by step05

How to use it

  1. Step 1: Measure the room

    Length and width at the widest points. For an L-shaped room, split it into rectangles, calculate each separately and add the areas before applying waste.

  2. Step 2: Read the carton coverage

    Printed on every box, usually as square feet per carton. This varies by product far more than people expect, so check rather than assume.

  3. Step 3: Choose the waste allowance

    Straight lay in a simple rectangle takes 10%. Diagonal or a room with alcoves and doorways takes 15%. Herringbone and chevron take 20%.

  4. Step 4: Order in one go

    Buy the whole quantity in a single order so every carton comes from the same dye lot.

Example usageWorked figures06

Example usage

A 20 by 14 living room
280 square feet plus 10% is 308. At 20 square feet per carton that is 15.4 boxes, so 16 — supplying 320 square feet and leaving 40 spare, which is a healthy repair stock.
The same room in herringbone
280 plus 20% is 336, needing 17 boxes rather than 16. One extra carton is the entire cost of the pattern in materials, though the labour difference is far larger.
A narrow hallway
Long thin spaces waste disproportionately because almost every board meets a wall. Push the allowance to 15% even for a straight lay in a corridor under four feet wide.
Frequently asked questionsCommon questions07

Frequently asked questions

How much waste should I allow for flooring?

Ten per cent for a straight lay in a rectangular room, fifteen for diagonal layouts or rooms with alcoves and multiple doorways, and twenty for herringbone or chevron. First-time fitters should take the next step up from whatever their layout suggests.

Why does buying from one dye lot matter?

Flooring is manufactured in batches and colour varies measurably between them. A carton bought weeks later can be visibly different under daylight, and on a continuous floor that difference is obvious.

Should I keep spare flooring?

Yes. A damaged board is a single-plank repair if you have matching stock and a much bigger problem if you do not, since the exact product may be discontinued by the time you need it.

Does this work for carpet?

Partly. The area calculation is the same, but carpet comes in fixed-width rolls rather than boxes, so the practical waste depends on how the roll width divides into your room. Broadloom is better estimated by a fitter.

Do I subtract anything for kitchen units or a fireplace?

Only for permanent built-in features covering a meaningful area. Most fitters run flooring under appliances and leave a consistent perimeter, so deducting small obstructions tends to leave you short.

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