Wallpaper Calculator
How many rolls of wallpaper a room takes, from the walls and their height less doors and windows, allowing for the pattern repeat.
Result…
How it's calculated
Wall area = perimeter × height − doors and windows Cut length = height + trim, rounded up to whole pattern repeats Drops per roll = roll length ÷ cut length, rounded down Drops = area × (1 + extra %) ÷ (roll width × height), rounded up Rolls = drops ÷ drops per roll, rounded up
Wallpaper is hung in drops (vertical strips) cut from the roll, so the number of rolls depends on how many whole drops each roll gives, not only on the area. The pattern repeat matters because each drop has to start at the same point in the pattern: the cut length is the wall height plus a trim allowance, rounded up to a whole number of repeats, and the rest of each roll is offcut. This calculator works out the wall area from the room or from each wall, takes off doors and windows, finds the drops at your roll width, and the rolls at your roll length. Roll sizes differ by country and maker, so enter the size on the label. Leaving small windows in the area gives you a safer margin. For painting instead, see the paint calculator.
Your numbers, step by step
About the Wallpaper calculator
This wallpaper calculator tells you how many rolls to buy for a room. Measure the room's length and width, or enter each wall you are papering, give the wall height and the area of doors and windows to leave out, then type the roll width, roll length and pattern repeat from the label. It works in metres and centimetres or in feet and inches. Wallpaper goes up in drops, so the answer comes from how many whole drops each roll gives: the cut length is the wall height plus a trim allowance, rounded up to whole pattern repeats, and the rest of the roll is offcut. That is why a large repeat can add rolls, and the result shows the count with and without it. Roll sizes differ by country and maker, so the calculator uses the size you enter. For painted walls instead, use the paint calculator.
How to use it
- Choose “Units”, then measure the walls by “Room length and width” or by “Each wall's width”.
- Enter the “Wall height” and the “Doors and windows (total area)” you won't paper.
- Copy the “Roll width”, “Roll length” and “Pattern repeat” from the wallpaper label.
- Set the “Trim allowance per drop” and “Extra for mistakes”, then read the rolls to buy and the drops per roll.
Worked example
A 4.5 × 3.6 m room with 2.4 m walls has 38.88 m² of wall; leaving out 4 m² of door and window gives 34.88 m². With 53 cm × 10.05 m rolls and 10% extra that is 31 drops. A 64 cm pattern repeat turns a 250 cm cut (2.4 m plus 10 cm trim) into 256 cm, so each roll gives only 3 drops and you need 11 rolls instead of 8. In feet, a 14 × 12 ft room with 8 ft walls, 40 ft² of openings and 20.5 in × 33 ft rolls needs 31 drops at 105 in each with a 21 in repeat: 11 rolls.
Updated
Questions people ask
How do I work out how many rolls of wallpaper I need?
Find the wall area less doors and windows, divide by the roll width times the wall height to get the number of drops, then divide by the whole drops one roll gives and round up. The calculator does this and shows each step.
How does the pattern repeat change the number of rolls?
Each drop has to start at the same point in the pattern, so its cut length is rounded up to a whole number of repeats. A long repeat can mean one fewer drop from every roll, which adds up over a room.
What size is a roll of wallpaper?
It depends on the country and the maker: much European wallpaper is about 0.53 m wide and 10 m long, while rolls sold in the US vary and are usually sold as double rolls (Selected Wallpapers compares the two). Always use the size printed on the label.
Should I take off the area of doors and windows?
Take off large ones such as doors and patio windows. Leaving small windows in gives you a margin for the awkward cuts around them.
Why buy a spare roll?
Colour can vary between production batches, so buy every roll with the same batch number and keep one for repairs. Ceilings, alcoves, stairwells and half-drop patterns need working out on their own.