Wallpaper Calculator

What this calculator does. It works out how many rolls of wallpaper you need to cover a wall (or a whole room's worth of walls added together), based on the height of the wall and the dimensions of the roll you're buying.

The formula in plain English. Drops needed across the wall = total width ÷ roll width, rounded up. Drops you can cut from one roll = roll length ÷ wall height, rounded down. Rolls = drops needed ÷ drops per roll, rounded up. The key insight is that you always round down when working out drops per roll (you can't cheat an inch on a drop) and always round up when working out rolls needed.

A worked example. A bedroom feature wall is 4 m wide with a 2.4 m ceiling. Using standard 0.53 m × 10 m rolls: 4 ÷ 0.53 = 7.5, rounded up to 8 drops needed. Each roll yields 10 ÷ 2.4 = 4 full drops. So 8 ÷ 4 = 2 rolls — order 3 to cover pattern matching and a spare for future repairs. For a full room of 12 m total wall width, the same maths gives 23 drops needed, 6 rolls minimum, so order 7.

Why this matters. Wallpaper is the DIY purchase most likely to go wrong on quantity. Buying too few rolls is almost guaranteed to mean a different dye lot on the top-up roll — visible as a faint vertical stripe down the wall for as long as you live with the paper. Buying far too many wastes £20–£40 per unused roll on mid-range patterns, and a lot more on designer brands. The right answer is "exactly enough plus one spare" — that's what this calculator targets.

When to use it. Specifying a feature wall, a full room or a stairwell; comparing two wallpaper ranges before buying; checking how much a larger-than-standard 0.68 m or 1.0 m wide roll will save against a standard 0.53 m roll; and pricing up a project where bold patterns push the roll count higher than you'd expect.

When not to rely on it alone. For murals, panoramic papers and digitally-printed bespoke designs, follow the manufacturer's measurement guide exactly — those are made-to-order and can't be topped up. For stairwells with high or angled walls, measure the longest drop carefully; a single mismeasurement on the tallest drop forces extra rolls.

Common mistakes. Forgetting the pattern repeat is the most expensive — bold prints with a 50 cm+ repeat can need 30% more paper than the basic maths suggests. Measuring only one wall and forgetting to add the others is the second. And not checking the roll width (designer ranges often aren't the standard 0.53 m) is the third. Painting the rest of the room? The paint calculator uses the same wall measurements you've already gathered.