How do I measure a room properly?

Rooms are almost never truly square or truly level, so a single measurement across the middle will let you down. Measuring in more than one place and recording which measurement is which is what stops you ordering the wrong quantity.

What you'll need

• Tape measure
• Notepad or phone
• Laser measure (optional)
• Second person (optional)

Step by step

1. Sketch the room roughly, including doors, windows, alcoves and any projections.It does not need to be to scale. It needs to be a place to write numbers.
2. Measure each wall at floor level, and note them on the sketch.Floor level, because that is where flooring and skirting go.
3. Measure the same walls again at about waist height.If they differ, the walls are out of true and you should use the larger figure for ordering.
4. Measure the ceiling height in at least two corners.Ceilings slope more often than people expect, particularly in older houses.
5. For paint, calculate wall area: perimeter multiplied by height, then subtract windows and doors.Then divide by the coverage on the tin and multiply by the number of coats.
6. For flooring, measure the widest point in each direction, including into doorways.Add 10% for cuts and wastage, more for a diagonal or patterned lay.
7. For wallpaper, measure the drop height and count the drops needed around the room.Add the pattern repeat to each drop, and always buy an extra roll from the same batch.
8. Record everything with units, and note what each measurement is for.A page of unlabelled numbers is useless a week later.

Tips

• A laser measure is inexpensive and far quicker for room dimensions, though a tape is still better for anything under a metre.
• Measure twice, order once. The cost of a second trip usually exceeds the cost of the extra material.
• Photograph the sketch with the measurements written on it, so it is on your phone when you are in the shop.

Common mistakes

• Measuring in one place only — Rooms are rarely square, and the difference between the widest and narrowest point is what causes a shortfall.
• Not adding a wastage allowance — Every flooring or tiling job produces offcuts. 10% is the usual minimum.
• Forgetting to subtract windows and doors for paint — It leads to buying substantially more paint than needed, though the error is at least in the safe direction.

Questions people ask