How to measure a wall for a wallpaper mural

Somewhere between falling for a design and actually ordering it, there is a tape measure and a small moment of doubt. Learning how to measure a wall for a wallpaper mural sounds like the fiddly part, mostly because every guide wants to teach you roll maths — total area, coverage per roll, extra for the pattern repeat, round up to nine rolls. Put all of that away. We print one mural for one wall, so we need two numbers from you, both in centimetres: the widest width and the tallest height. That is the whole brief. The rest of this is about making those two numbers right.

Why the roll maths doesn't apply to a mural

Most measuring guides you find online, English or Thai, are written for wallpaper sold by the roll — around 53 to 54 cm wide, fixed length, a pattern that has to line up strip to strip. So it teaches you to divide your area by what one roll covers, add for the repeat, and buy a spare. Sound advice for that product, and not this one. A mural is a single image sized to a single wall: nothing to divide, no repeat to match, no spare roll in the cupboard. Your two measurements are the order, which makes the job much shorter and slightly less forgiving.

Measure three times, and take the biggest number

Walls are not as honest as they look. Plaster builds up in corners, floors slope, ceilings dip. A wall measuring 302 cm at the top can easily be 305 cm along the skirting, and if you order for 302 you will spend your installation afternoon looking at a three-centimetre stripe of old paint.

Take a steel tape rather than a soft dressmaker's one, which sags over three metres and reads short. Then:

• Width, three times — along the top, across the middle, and low down near the floor.
• Height, three times — hard against the left corner, in the centre, and hard against the right corner.
• Use the largest of each set. Not the average, not the middle one. The largest.

Trimming a few extra millimetres at the edge takes seconds with a sharp blade. A gap does not fix itself.

What to do about the skirting board

This is where most people pause, and the answer is a decision rather than a rule: measure only the surface you actually want covered.

If the skirting is staying — which it usually is — your height runs from the top edge of the skirting to the ceiling, not from the floor, at all three points. If your fitter is taking the skirting off and refitting it over the mural, measure to the floor instead and you gain a very clean bottom edge for your trouble.

The same applies above: cornice, coving or a lighting cove means measuring to the underside of it. Whatever you decide, be consistent across all three readings — half from the floor and half from the skirting is how people end up with a mural that fits nowhere.

Sockets, doors and windows: measure straight through them

Here is the instruction that feels wrong and is right: do not subtract anything. Measure the wall as though it were completely empty — no plug sockets, no light switches, no door, no window. We print the full rectangle and the openings get cut out once the panel is up and positioned, which is far easier than lining up a pre-cut hole with a socket that turns out to be a centimetre off.

Deduct a window and two things go wrong at once: the mural comes up short, and the part of the design you fell in love with lands somewhere you never intended. Which is a good moment to say you can see a design on your own wall at your real size first — set the width and height there and the numbers carry through to the product page, so you can see where the horizon or the tallest leaf will land relative to your sofa.

Aircon units, pelmets and built-in wardrobes

These are the Thai-condo edge cases nobody covers, and each is the same question: does the mural run behind the obstacle, or stop at it? Decide before you pick up the tape, because the answer changes your height or your width.

• A wall-mounted aircon unit. If the mural stops beneath it, your height is skirting to the underside of the unit. If it runs behind — usually the better-looking choice, since you are not drawing a line across the wall — measure the full height and let your fitter cut around the bracket. A curtain pelmet or boxed-in bulkhead is the same decision.
• A built-in wardrobe against one end. Tucking behind it means measuring the full wall corner to corner. Stopping at its edge means measuring to that edge and adding a centimetre or two, so the join is covered rather than exactly met.

What bleed is, and why we ask for the wall not the paper

Bleed is the extra printed edge we add beyond your measurement, so the design reaches into the corners with no thin white line where the wall meets the ceiling. We add 5 cm on every side, automatically. Enter a wall of 300 × 260 cm and we print 310 × 270 cm; you trim the surplus as you hang.

So the one thing not to do is add your own margin. Round 300 up to 310 to be safe and we add our five centimetres on top, and you end up trimming away real artwork and paying for area you never had. Give us the wall. We handle the maths.

As you type, the product page keeps a running note of your coverage area in square metres and how the mural will arrive — a set of equal vertical panels, each no wider than the material's roll, numbered so they go up in order. Panel widths vary by material, one of several reasons the materials page is worth a read before you commit.

A short checklist before you enter the numbers

• Whole centimetres. The fields take centimetres, not metres or inches. A wall 2.6 m tall is 260.
• Know the range. Widths run 50 to 600 cm and heights 50 to 400 cm, and some designs set their own range within that — the design's page shows you its limits as you type. Bigger or stranger than that, message us first.
• One wall, one measurement set. Two walls means two murals and two pairs of numbers, not one long one.
• Photograph the tape. A picture of the tape against the wall, number readable, beats a figure half-remembered at the checkout page.
• Order free A4 samples if you are undecided on finish. Every mural is printed to your wall, which is lovely, and also means no change-of-mind return once printing starts. Measure twice, order once.

Questions we get asked

Do I subtract the window or the door?

No. Measure the wall's full width and height as if they weren't there, and cut the openings during installation.

My wall is 3 cm wider at the bottom. Which do I use?

The bottom — always the larger figure. The extra sits in the trim and disappears. The shortfall would not.

Do I need to add anything for the bleed?

No. The 5 cm per side is added after you enter your size, so enter the wall exactly as you measured it.

What if my wall slopes or isn't flat?

Measure the longest and widest points and treat it as a full rectangle. Slopes, angles and the odd curve get trimmed to shape when the mural goes up. If the surface itself is rough — textured render or bare block rather than smooth plaster — get it smooth and clean first, then measure over the finished surface. How it works covers the steps either side of that.

That is genuinely all of it: two numbers, taken three times each, in centimetres. Then the pleasant part — hold them up against something broad and botanical, a landscape like Roerich Valley that brings light to a wall that doesn't get much, or everything we print with your dimensions already in mind. Choose your size and see it on your wall.