Why Getting the Numbers Right Matters

Flooring is one of those purchases where a small measuring error can snowball. Order too little and you risk a second delivery that doesn't quite match the first batch, or a delay while you wait for more stock. Order far too much and you're paying for boards or tiles that sit in the garage for years. Either way, the cost lands on you.

The good news is that measuring is straightforward once you know what to record and where people usually slip up. Set aside twenty minutes, grab a tape measure, a pencil, paper and a helper if you have one.

Start With a Rough Sketch of the Room

Before you measure anything, draw the shape of the room on your paper. It doesn't need to be to scale — it's simply a place to jot numbers so you don't lose track of which wall is which. Mark the doorways, alcoves, chimney breasts, pipe boxing and built-in cupboards.

Then measure at floor level, not at waist height. Walls bow, skirting boards have thickness and plaster isn't always plumb, so measuring up high can easily leave you 5–10cm out across the width of a room.

Measuring a Straightforward Rectangular Room

Even a simple room deserves two measurements in each direction, because very few rooms are perfectly square. Here's the approach:

• Measure the longest point wall to wall, noting it in metres to two decimal places.
• Measure the widest point, again wall to wall.
• Repeat both at the opposite end of the room. If the figures differ, use the larger.
• Measure the two diagonals, corner to corner. If they match, the room is square. If they don't, allow a little extra for cuts and plan your starting line carefully.
• Multiply the longest length by the widest width for your square metre figure.

Record your working on the sketch, for example "4.32m x 3.18m = 13.74 sq m". It makes checking your sums much easier later.

Dealing With Awkward Shapes

L-shaped rooms, alcoves and bay windows are common in UK homes, and they're where most mistakes happen. The trick is to break the floor plan into rectangles, measure each one, then add them together.

• For an L-shape, draw a line to split it into two rectangles, work out the area of each, then add them.
• For a bay window, treat the recess as its own small rectangle and measure at the widest point, not across the window frame.
• For alcoves or chimney breasts, measure the full width of the room including the recess, then record the recess separately if it helps.

Don't subtract areas for small obstructions unless the flooring genuinely cannot be laid there. It's far safer to keep them in and let your fitter trim around them.

Don't Forget Doorways, Recesses and Thresholds

This is the step people skip, and it's the one that leaves them a plank short. Flooring rarely stops neatly at the door frame — it carries on into the doorway, under the architrave and up to the threshold strip.

• Measure the depth of every doorway you want the flooring to run into.
• Note the width of door openings in case your chosen plank or tile has a direction and needs cutting around the frame.
• Include any cupboard floors you're covering — if the flooring runs into a built-in wardrobe, that area counts.
• Check whether skirting boards are staying. If they are, measure to the face of the skirting and remember your fitter will need to scribe around it or add beading.

Add these figures to your sketch as separate small areas rather than trying to squeeze them into the main room calculation.

Adding an Allowance for Cuts and Wastage

No installation uses exactly the square metreage of the room. Cutting around door frames, staggering joints, matching patterns and simply getting things wrong all consume material. The amount you add depends on the product and the layout:

• Straight lay, standard planks or tiles: add 5–7%.
• Diagonal or diamond patterns: add 10%.
• Herringbone or chevron: add 15% or more, as the pattern generates far more offcuts.
• Patterned tiles that need matching: add 10–15% so you can line the pattern up.
• Keep a spare pack: invaluable for future repairs, as dye lots vary between production runs.

To apply the allowance, multiply your total square metreage by 1.05 for 5%, 1.10 for 10%, and so on. Round up to the next whole pack or box — that's the figure you order.

Double-Check Before You Order

Before you hand over your figures, run through this quick checklist:

• Have you measured at floor level, at the widest and longest points?
• Are doorways, alcoves and cupboard floors included?
• Have you added the right wastage allowance for your layout?
• Are your units consistent — all in metres or all in centimetres?
• Does the product's pack coverage match your total?

If in doubt, ask the retailer or your fitter to sense-check the numbers before ordering. Five minutes of checking is far cheaper than a return delivery or a paused installation — and it means that when the flooring arrives, you can get straight on with laying it.