Wallpaper quantity calculator

Wallpaper quantity calculator#

Enter the room, the roll and the pattern repeat. The calculator returns the number of drops, the usable drops per roll after the repeat is allowed for, and the rolls to order.

Inches Centimetres

Wall length to cover in

Wall height in

Roll width in

Roll length in

Pattern repeat (0 for plain) in

Doors and windows to deduct

Enter your measurements above.

A standard European roll is 53 cm x 10.05 m (20.9 in x 33 ft). US rolls vary; enter what is printed on the label. Openings are only deducted at half value, because the offcuts around them are rarely reusable.

Nothing you type leaves your browser: the maths runs on this page, and no values are stored or sent anywhere.

Enter the wall length, the wall height, the roll size and the pattern repeat, and the calculator returns the number of drops, how many of those drops a roll actually yields, and the rolls to order. Everything happens in your browser as you type: nothing is stored and nothing is sent anywhere. It is a planning figure, so check it against the roll label before you buy.

Drops, not square feet#

Every wallpaper estimate that goes wrong goes wrong in the same place. Paper is sold by area but hung in fixed-width strips, and a strip cannot be narrowed without a seam. The unit of the job is therefore the drop: one full-height length of paper, the width of the roll.

The calculator works in that unit throughout. It divides the wall length you give it by the roll width and rounds up, which gives the number of drops. It then works out the cut length of one drop, divides that into the roll length and rounds down, which gives the usable drops per roll. The order is the first number divided by the second, rounded up again. Three roundings, all in the same direction as the cost.

The wall length you enter is the run to be papered, measured along the wall rather than around the room on a plan. Take it the way how to measure a room properly sets out, at hand height rather than along the skirting, and if the room is visibly out of square measure each wall separately and add them. The tolerances involved are covered in out of square rooms and tolerance.

The arithmetic, worked once by hand#

A 12 x 8 ft room, papered to a standard 8 ft ceiling, with a mid-scale patterned paper on a 21 in repeat and two openings.

1. Wall length. Two walls at 12 ft and two at 8 ft is 40 ft, or 480 in (12.2 m).
2. Cut length. The wall is 96 in. Divide by the 21 in repeat: 4.57, which rounds up to five whole repeats, or 105 in. Add the 4 in trim allowance, 2 in at each end, and the cut length is 109 in (277 cm).
3. Drops per roll. A 33 ft roll is 396 in. Divide by 109: 3.63, which rounds down to three usable drops. The remaining 69 in is not long enough for a fourth.
4. Number of drops. 480 in of wall divided by a 20.5 in roll width is 23.4, rounded up to 24 drops.
5. Openings. Two, deducted at half a drop each, so one drop comes off: 23 drops.
6. Rolls. 23 divided by three is 7.67, so eight rolls.

Eight rolls yield 24 drops for 23 needed, so one spare drop comes out of the job. An area-based estimate on the same room, 40 ft of wall at 8 ft high less openings, gives about 290 sq ft against 56 sq ft of gross paper per roll, which says six rolls. The two-roll gap is the repeat and the offcuts, and it is entirely predictable.

Roll sizes you will actually meet#

Note the third row. The wide US roll carries more paper but in a shorter length, so on a tall wall it yields fewer drops and can order out worse than the narrow one despite the bigger area on the label. Roll width also sets the seam spacing, which is a visual decision as much as a quantity one: a 20.5 in roll puts a seam every 20.5 in across the wall, and on a panelled wall those seams want to land in a sensible relationship with the stiles, as wainscot and wall panelling heights discusses.

Where judgement replaces the arithmetic#

The half-drop deduction for openings is a working average, not a rule. A full-height French window removes close to a whole drop of paper, and a small high-level window in the middle of a wall removes almost none, because the strips above and below it still have to be cut from full drops to keep the pattern in line. If your openings are unusual, count the drops on a sketch elevation instead and enter that number of drops directly as wall length divided by roll width.

Ceiling height is the other judgement call. Enter the tallest drop on the wall, not the average, and remember that ceiling heights vary between countries and eras: the differences are laid out in ceiling heights by country. If the room has a deep skirting or a picture rail, measure the papered field only, from the top of the baseboard or skirting to the underside of the cornice, rather than floor to ceiling.

What the calculator deliberately does not do#

• It does not model an offset or drop match, which typically halves the repeat waste. Treat the result as the straight-match case and the upper bound.
• It does not paper ceilings, reveals or the returns into a window opening. Add those as extra wall length, taking the depths from window sill and head heights.
• It does not add for pattern centring on a chimney breast, which usually costs one extra drop per feature wall.
• It does not price lining paper, paste or the sizing coat. For the equivalent arithmetic in paint, use the paint quantity calculator.
• It does not convert roll sizes between systems. Put the label figures through the interior unit converter first if the roll is metric and your room is not, or take the standing tables in fabric and drapery conversions.

The other quantity tools are listed with the rest of the interior dimension calculators.