How to Measure a Room for Flooring

What you need

A tape measure, a pencil and paper (or your phone), and the room empty enough to reach the walls. Measure in feet or metres — whichever your supplier uses — and write down every number as you go.

Step 1 — Measure the length and width

Measure the longest wall (length) and the wall at right angles to it (width), wall to wall, at floor level. Measure twice: once near each end of the wall, and use the larger number — walls are rarely perfectly straight.

Step 2 — Deal with irregular shapes

For an L-shaped room, split it into two rectangles, measure each one, and add the areas. For a bay window or alcove, measure it as its own small rectangle and add it. Never try to measure an irregular room as one rectangle — you will over-order or under-order.

Step 3 — Subtract nothing, add wastage

Do not subtract doorways or small fixtures from the floor area — the wastage allowance covers them. Add 10% for straight-lay flooring (tiles, planks, laminate) and 15% for diagonal lays or patterned tiles, where cuts waste more.

Step 4 — Work out the quantities

Multiply length by width for the area, add the wastage, then divide by the coverage per box or pack. Use the calculators below — they do the arithmetic and round up to whole boxes, because you cannot buy part of a box.

Worked example

A room 12 ft × 10 ft is 120 ft². Add 10% wastage: 132 ft². If one box covers 20 ft², you need ceil(132 ÷ 20) = 7 boxes. That is exactly what the flooring calculator gives you.

Common mistakes

• Measuring the room, not the floor. Measure wall to wall at floor level — skirting boards do not count.
• Forgetting the wastage. Every cut wastes material. 10% is the minimum for a rectangular room.
• Mixing units. Do not mix feet and metres in one measurement. Pick a unit and stick to it — or let the calculator convert.

Safety

Measuring is low-risk work, but take care with the tape: keep your fingers clear of the blade and let it retract slowly — a snapping tape can cut. Kneel on a pad or a folded towel on hard floors, and get help moving heavy furniture instead of dragging it across the floor you are about to measure.

When to hire a professional

Hire a flooring installer if the floor is uneven and needs levelling, if the subfloor is damaged or damp, or if the room has curved walls or several levels. Installers usually measure as part of the quote, and their measurement is the one the order is based on — so let them measure before you buy.

Frequently asked questions

• How accurate do my measurements need to be? Measure to the nearest centimetre or eighth of an inch, and always round up, never down. A centimetre lost on every wall is a box short at the end.
• How do I measure a round room? Measure the diameter across the widest point and work out the area from that. Our guide to measuring round or angled spaces shows the method step by step.
• Should I buy a spare box? Yes — one spare box of the same batch, kept for future repairs. Flooring batches change colour slightly, and a box bought later may not match.
• What if the flooring is sold by the pack, not the box? Divide your total area (with wastage) by the coverage per pack and round up to whole packs.

Try these calculators

• Square Footage Calculator — the room's area in ft², m², yd² and acres.
• Flooring Calculator — boxes, planks and cost for the room.
• Tile Calculator — tiles, boxes and grout for a tiled floor.