Wallpaper Calculator

CALCULATION METHOD

How many rolls of wallpaper do I need?

Wallpaper is installed as full-height vertical strips. First calculate how many strips span the wall width. Then adjust each strip length upward to a complete pattern repeat, determine how many complete strips fit on one roll, and round the roll count up.

Strips needed = wall width ÷ roll width, rounded up

Minimum strip = wall height + trim allowance

Matched strip = minimum strip rounded up to the next pattern repeat

Strips per roll = roll length ÷ matched strip, rounded down

Rolls = strips needed ÷ strips per roll, rounded up

12 × 10 room example

A 12 ft × 10 ft room has a 44 ft perimeter. With 8 ft walls, 20.5-inch-wide paper, a 33 ft roll, a 20.5-inch repeat, and 4 inches of trim allowance, the room needs 26 full-width strips. Three matched strips fit on each roll, so the calculated order is 9 rolls before any optional spare.

How pattern repeat changes roll count

The vertical repeat is the distance before the design starts again. Each strip must begin at the correct point for adjacent motifs to align, so a matched strip can be longer than the wall. Enter the repeat printed on the wallpaper label; enter zero for a plain or random-match product.

Standard US wallpaper roll size

York describes a common US bolt as 20.5 inches wide by 33 feet long, with about 56 sq ft of nominal material. Product sizes vary, and pattern matching reduces usable full-height coverage, so the calculator uses the physical dimensions from your label rather than assuming every roll covers the same wall area.

Should I subtract doors and windows?

This calculator intentionally counts complete floor-to-ceiling strips and does not automatically subtract ordinary openings. Pieces above and below openings still require pattern alignment, and their offcuts may not be reusable. For a large full-height gap, use Wall width mode and enter only the continuous widths you will paper.

Single rolls, double rolls, and bolts

Wallpaper may be priced using a single-roll convention but packaged as a longer double roll or bolt. Enter the physical length and price of the package you will actually buy. The result then reports physical packages rather than pricing units.

Method references

York Wallcoverings calculator and roll chart for the common 20.5 in × 33 ft bolt and repeat warning; Sherwin-Williams wallpaper ordering guide for pattern-repeat and dye-lot considerations. Accessed September 11, 2026.

Wallpaper calculator FAQs

How many rolls do I need for a 12 × 12 room?

The answer depends on ceiling height, roll dimensions, and pattern repeat. With 8 ft walls, 20.5-inch-wide × 33 ft rolls, a 20.5-inch repeat, and 4 inches of trim, the four walls require 29 strips and 10 physical rolls.

What is wallpaper pattern repeat?

It is the vertical distance before the design repeats. Matched patterns may require each strip to be cut longer so adjacent motifs line up.

Why does this calculator use strips instead of square feet?

A roll can only produce a whole number of full-height strips. Area-only division can count leftover pieces that are too short to hang as another strip.

Should I order an extra roll?

An extra roll can cover miscuts, damage, future repairs, and layout differences. Use the Extra rolls field when appropriate and try to buy every roll from the same dye lot.

Does a double roll mean I enter two rolls?

No. Enter the physical width and total length of the package sold to you. If the product is a 33 ft double roll or bolt, enter 33 ft and count it as one physical package.