How much flooring do I need?

The honest answer is not just the size of the room. Measure the area, add for waste, then turn it into whole boxes. Here is each step.

By the Calculator Den team · Updated 2026-10-29

Working out how much flooring to buy trips people up because the honest answer is not just the size of the room. Buy exactly the floor area and you will run short, because every installation wastes some material on cuts, mistakes and matching the pattern. Order far too much and you waste money. The reliable method is three steps: measure the real area, add the right amount for waste, then convert that into whole boxes. Here is how to do each one.

Step 1: measure the floor area

Start with the actual area to be covered. For a simple rectangular room, multiply length by width: a room 5 m by 4 m is 20 square metres, and a room 15 ft by 12 ft is 180 square feet. Work in whatever unit your flooring is sold in, metres or feet, and keep to it throughout so you are not converting at the end.

Most rooms are not perfect rectangles. For an L-shaped room, an alcove or a chimney breast, split the floor into rectangles, work out each one, and add them together. Only subtract an area you genuinely will not floor, such as under fitted kitchen units or a large permanent island; for anything small, leave it in, because the offcuts rarely help you elsewhere. Floating floors are often run under or around such units, so when in doubt, include the area. If you want the measuring itself laid out step by step, our guide on how to calculate square footage covers odd shapes in detail.

Step 2: add a waste factor

This is the step beginners skip, and it is why they run short. You always need more flooring than the bare floor area, because planks and tiles get cut at the walls, some are damaged, and patterned layouts throw away more. The extra is the waste factor, added as a percentage on top of your area. How much depends on the floor and the layout:

5 to 10%: a simple rectangular room with straight-lay plank, laminate or vinyl and few cuts. Use 10% as a safe default for a normal home with doorways and a closet or two.
10 to 15%: hardwood and tile, or rooms with lots of angles, nooks and doorways.
15 to 20%: a diagonal layout, where planks or tiles meet the walls at 45 degrees (tile on the diagonal sits at the higher end).
15 to 20%: herringbone, chevron and other patterns that cut a lot of material.

These percentages are a rule of thumb, not a fixed standard. Where the flooring manufacturer or your installer gives a figure for your specific product and layout, use theirs, because they know how that material cuts. To apply it, multiply your area by one plus the percentage. For 20 m² at 10% waste, that is 20 × 1.10 = 22 m². For 180 sq ft at 15% for a diagonal lay, 180 × 1.15 = 207 sq ft. When in doubt, round the waste up rather than down, because a spare box is cheap insurance and being half a box short mid-job is not.

Step 3: turn area into boxes

Flooring is sold by the box, and each box covers a set area printed on the label, often somewhere between about 1.7 and 2.8 m² (18 to 30 sq ft), with metric packs commonly around 2.0 to 2.5 m². To find how many boxes you need, divide your area-with-waste by the coverage per box, then round up to the next whole box every time. You cannot buy most flooring by the single plank.

Say you need 22 m² and each box covers 2.2 m²: 22 ÷ 2.2 = 10 boxes exactly, so buy 10. If the sum had come to 10.2, you would buy 11. A worked example in feet: a 180 sq ft room at 10% waste is 198 sq ft; at 20 sq ft per box that is 198 ÷ 20 = 9.9, so you buy 10 boxes. Keep one unopened box or a few spare planks after the job for future repairs, because dye lots change between production runs and an exact match later is hard to find.

Do not forget the extras

The planks are not the whole order. Most floating floors need underlay, sold by the roll and measured the same way, by area. You may also need trim or beading around the edges (measured by the running length of the walls, not the area), a threshold strip at each doorway, and adhesive or tape depending on the type. Pricing these alongside the flooring stops a nasty surprise at the till.

A quick worked example

Take an L-shaped living room made of a 5 m by 4 m rectangle plus a 2 m by 2 m alcove. The area is (5 × 4) + (2 × 2) = 20 + 4 = 24 m². It is a normal room with a couple of doorways, so add 10%: 24 × 1.10 = 26.4 m². The laminate covers 2.4 m² per box, so 26.4 ÷ 2.4 = 11 boxes exactly. Add a few rolls of underlay to match the area and the beading for the room's perimeter, and the order is complete.

Measuring tips that save money

A few habits prevent the two expensive mistakes, running short and massively over-ordering. Measure each room at its widest points, and in more than one place, because walls are rarely perfectly square and the larger figure is the safe one to buy against. Draw a quick sketch with the measurements on it, so when you split an odd shape into rectangles you do not count a strip twice or miss an alcove. Measure into doorways and closets if the floor runs through them, since that area needs covering too. And if your flooring is sold in one unit but you measured in another, convert before you order: one square metre is about 10.76 square feet, so 20 m² is roughly 215 sq ft. Getting the unit right matters as much as getting the number right.

The bottom line

Measure the real area, splitting odd shapes into rectangles; add a waste factor that fits your floor and layout, from about 10% for a plain room up to 17% or more for herringbone; then divide by the coverage per box and round up. Keep a spare box for repairs and remember the underlay and trim. To do the area sum quickly, including L-shapes, use our square footage calculator, and when you are comparing two floors on price, the unit price calculator turns a price per box into a price per square metre or foot so you compare like with like.