Built by people who spent years on the ladder before they ever built a website.

How much wallpaper do I need?

It’s the first question every project starts with — and it’s the easiest one to get wrong. Order a roll too few and your job stops dead while you wait for a second batch that may not even match. Order too many and you’ve paid for rolls that sit in a cupboard forever. The calculator below exists to get you the right number the first time, using the same math we relied on for years when being short by a single roll meant a return trip and an awkward phone call.

Enter your wall size and a few details from the product’s spec sheet, and it tells you exactly how much to buy — accounting for the pattern repeat and the way strips are actually cut from a roll, not a rough “square footage divided by coverage” guess.

Tip: Every product page on our store has this calculator built in, and it reads that paper’s spec automatically — so once you’ve picked a wallpaper, you don’t even need to type the roll details. This page is the general version for planning ahead or working from a spec sheet in hand.

From the ladder to your screen

Wallpaper Twins didn’t start behind a keyboard. We started on ladders — trowels, seam rollers and sharp knives in hand. For years we hung wallpaper for a living: living rooms and nurseries, hotel lobbies and restaurant feature walls, narrow stairwells with ceilings that never quite agreed with the floor. We learned the trade the way you only can by doing it — measure twice, cut once, match the pattern across a dozen drops, and plan around the repeat so a finished room looks seamless instead of patched together.

When we moved into e-commerce, we didn’t leave that knowledge on the job site. We poured it into this calculator. Every number it returns comes from the same working method we used on real walls, for real clients, where a bad estimate cost us time and money. That’s why we trust it — and why you can too. It isn’t a generic widget bolted onto a store by someone who’s never hung a strip in their life. It’s the estimating method of working installers, written down.

How the calculator works

Most online calculators take your wall area, divide by the coverage printed on the roll, and call it a day. That’s how people end up short. Real walls don’t work in tidy squares. Here’s what ours actually does:

It plans around the pattern repeat

Wallpaper has a pattern repeat — the vertical distance before the design starts over. For the pattern to line up seamlessly across your wall, every strip has to begin at the same point in the design. That means each strip is cut a little longer than your wall is tall, so it can be slid up or down to match its neighbour. Our calculator rounds every drop up to the next full repeat before it works anything out. The bigger the repeat, the more material a pattern needs — and this is the single biggest reason cheap estimates fall short.

It counts strips the way a roll is really cut

You can’t splice the leftover piece at the bottom of a roll onto the top of your next strip — the pattern wouldn’t match and the seam would show. So we work out how many full-height strips you actually get from one roll, then how many rolls that takes. The offcuts aren’t counted as usable material, because on a real wall they aren’t.

It always rounds up

We never round down. If the math lands at 4.1 rolls, you need 5. A spare roll tucked away for a future repair is cheap insurance; a bare patch of wall three weeks into a backorder is not.

It keeps you in one dye lot

Wallpaper is printed in batches called dye lots, and colours can shift slightly between them. Because the calculator tells you the full quantity up front, you can order it all at once and we can ship it from a single lot — so your walls match edge to edge. Run short later and the replacement roll may be a shade off.

It handles rolls and yardage

Some papers are sold by the roll, some by the yard, and some ship as continuous double rolls. The calculator handles each — on a product page it reads the selling method straight from the spec, and here you can pick it yourself. Murals and made-to-measure panels are a different animal: they’re sized to your exact wall, so for those we’d rather spec it with you by hand than hand you a number.

How to use it

Measure the width and height of the wall you’re papering, in feet and inches (or switch to metric). If you’re doing several walls of the same size, set the number of walls. Then add your paper’s roll width, roll length and pattern repeat — all three are listed on the product’s spec table — and choose whether it’s sold by the roll or the yard. The answer updates as you type.

A few things worth knowing: don’t subtract for doors and windows. It feels wasteful, but that “extra” is exactly the safety margin and the offcut stock a professional wants on hand — and openings rarely save you a whole strip anyway. For walls of noticeably different widths, run each one separately and add them up. And when in doubt, order a sample first: it lets you see the colour in your own light and confirm the repeat before you commit to the full quantity.

When to just ask us

Some rooms don’t fit a formula — sloped and vaulted ceilings, stairwell walls that change height as they climb, a huge single feature wall, or a commercial job where getting it wrong is expensive. That’s the kind of thing we used to work out on site with a tape measure and a pencil, and we still will. Send us your dimensions and a photo and we’ll spec it by hand, the same way we would if we were standing in the room. Because at the end of the day, the calculator is only as trustworthy as the people who built it — and we’ve actually hung the paper.