Wallpaper Calculator

Common questions

How many rolls of wallpaper do I need?

Take the worked example on the page: 40 ft of wall 8 ft high, papered from a 20.5 in by 33 ft roll with a 19 in straight repeat. Each drop needs the 8 ft of wall plus the 4 in trim allowance, which is 8 ft 4 in, and rounding that up to six whole repeats of 19 in makes the cut 9 ft 6 in. A 33 ft roll gives three of those and the 4 ft 6 in left on the end is not a fourth. The 40 ft of wall divided by the 20.5 in roll width, rounded up, is 24 drops. 24 drops at three a roll is 8 rolls.

What does the pattern repeat do to the number of rolls?

It lengthens every drop, because each one has to start at the same point in the design. On that same wall the repeat turns an 8 ft 4 in drop into a 9 ft 6 in cut, so 1 ft 2 in is cut off each of the 24 drops. The effect is stepped rather than smooth: raise the ceiling from 8 ft to 9 ft and the cut is still 9 ft 6 in, because 9 ft 4 in still fits inside the same six repeats, and the order is still 8 rolls. A paper with no repeat, or a free match, is cut to the wall itself and nothing is rounded.

How does a half-drop match change the cut length?

On a half-drop, or offset, match every other drop starts half a repeat further along the roll, so the page adds that half repeat to each cut. The 9 ft 6 in cut becomes 10 ft 3.5 in. On the example wall a 33 ft roll still yields three drops, so the order is still 8 rolls, but the margin is thinner: the length left on the end of each roll falls from 4 ft 6 in to 2 ft 1.5 in. A hanger who cuts drops in pairs can win some of that back, which is why the allowance is shown as its own figure rather than hidden in the total.

Should I take the doors and windows off?

That is your call, and nothing comes off unless you make it. The page opens on papering over every opening, because drops still run past a window and the offcut is rarely another drop. Set it to floor-to-ceiling only and openings at least 80 percent of the wall height come off while shorter ones stay in: a 3 ft door on the example wall takes the 24 drops to 22, which is still 8 rolls with two drops spare. Set it to every opening and a 3 ft door with two 3 ft windows takes it to 19 drops and 7 rolls.

Why not just divide the wall area by the area printed on the roll?

Because that spends the offcut you cannot use. The 24 drops in the example are 228 ft of paper and a roll is 33 ft, so an area or length calculation says 6.9 and buys seven rolls. Hung in drops, a roll gives three 9 ft 6 in drops and 24 drops need eight rolls. The same floor works the other way too: with no repeat and a 7 ft 9 in wall the cut falls to 8 ft 1 in, four drops come off each roll, and the same 24 drops need only 6 rolls. The roll count moves in steps because whole drops do.

Does it work in metres, and with European rolls?

Yes, and each measurement keeps its own unit, because a roll is quoted 53 cm wide by 10.05 m long and a wall is measured in metres. The metric worked example is a 4 by 3 m room, so 14 m of wall, 2.4 m high with a 10 cm trim allowance and a 60 cm repeat: the 2.5 m a drop needs rounds up to five whole repeats, which is a 3 m cut, a 10.05 m roll yields three of those, and the 27 drops come to 9 rolls. Feet and inches are read as written as well, so 8' 6" and 8.5 both work.

What is the trim allowance, and can I change it?

The trim allowance is the spare added to a drop for trimming at both ends together. It starts at 4 in and is editable: enter 0 for no extra length. The wall height plus this allowance is then rounded up to whole pattern repeats when the paper has a matched design.

Is anything uploaded?

Nothing is uploaded and no account is needed. Wall and roll dimensions, repeat, trim and openings are remembered in this browser. Cost entries stay only while the page is open. Copy puts the quantity plan and any valid cost breakdown on your clipboard.

How do I measure one wall or a whole room?

For one wall, enter its width as Wall run and its floor-to-ceiling height as Wall height. For several walls of the same height, add their widths. For a rectangular room, enter Room width and Room length, then choose Use the run around it. Estimate different-height sections separately and add their rolls.

Can I calculate wallpaper in inches, centimetres or linear yards?

Use the ft, in, m or cm buttons for plain numbers. A measurement may also include its unit, such as 8 ft 6 in or 11 yd; one yard is 3 ft. The result reports Linear yards bought from the whole rolls, separately from the length in cut drops. Square footage describes wall area; it does not account for pattern matching or roll offcuts.

How do double rolls, peel-and-stick rolls and wide commercial rolls work?

Enter the actual width and length on the package. The 20.5 in by 33 ft button is a double-roll size; the 20.5 in by 16.5 ft button is a single-roll size. A counted roll means one length matching your entered dimensions. Roll-based peel-and-stick paper uses the same drop arithmetic. Precut panels and murals need their own layout.

Can I calculate wallpaper for a ceiling?

Estimate a flat rectangular ceiling separately: use its width across the strips as Wall run and the length of a strip as Wall height. Enter the roll size, repeat and trim for that rectangle. This is a quantity calculation; it does not model slopes or provide hanging instructions.

How is wallpaper installation cost calculated?

Open Installation cost from your rates and enter Price per roll, Installation rate per area unit and any Other charges. Material is whole rolls multiplied by your roll price. Installation is gross wall area multiplied by your rate per sq ft or m², rounded to two decimal places with a half cent rounded up. Other charges are added once. Door and window deductions affect rolls, but do not reduce this installation area. Use one currency and enter 0 for an excluded component; local rates and extra charges are not supplied.

Can I use the roll formula in Excel?

For a straight match with positive repeat, using one unit throughout: cut length = CEILING.MATH((height + trim) / repeat) * repeat; drops = CEILING.MATH(run / roll width); drops per roll = FLOOR.MATH(roll length / cut length); rolls = CEILING.MATH(drops / drops per roll). With no repeat or a free match, cut length = height + trim. This assumes no opening deductions and at least one drop per roll.