Wallpaper Pattern Repeat Calculator

Explanation

Wallpaper estimation is a finish detail where pattern repeat has a large effect on material quantity. The roll length might cover a wall by area, but if the pattern must align between strips, each strip has to be cut longer than the wall height. That extra length is waste, but it is required to keep the pattern consistent from strip to strip. This calculator models that by rounding each strip length up to the next pattern repeat.

First, the tool computes how many vertical strips are required to cover the wall width: wall width divided by roll width, rounded up. Next, it adjusts the strip length for pattern repeat. If the repeat is zero, the strip length is simply the wall height plus trimming allowance. If the repeat is non-zero, the strip length is rounded up to the next full repeat. The number of strips per roll is the roll length divided by that adjusted strip length. Finally, the calculator divides the total strip count by strips per roll to estimate rolls needed. This process produces a more realistic roll count than simple area division.

The effective coverage per roll represents how much wall area you actually cover after pattern alignment waste is included. This value is especially helpful for budgeting and verifying supplier recommendations. It also makes it easy to compare different wallpaper products with different roll sizes or repeat distances. For multi-wall rooms, sum the wall widths and repeat the calculation, or run individual wall calculations and add the roll totals. As always, add a spare roll for repairs or future touch-ups if the pattern is unique or difficult to match.

Use the same unit system for each measurement: wall width and height, roll width and length, and pattern repeat. Mixing inches with millimeters or feet with meters will distort the strip length and roll count. When in doubt, verify roll specifications on the label and convert units before you enter them. This keeps the repeat alignment logic accurate and ensures the roll estimate stays realistic for ordering.

Formula

Strips needed: strips = ceil(wallWidth / rollWidth)

Adjusted strip length: strip = ceil(wallHeight / repeat) x repeat (if repeat > 0)

Strips per roll: perRoll = floor(rollLength / strip)

Rolls needed: rolls = ceil(strips / perRoll)

Example Calculation

A 12 ft wide wall with a 9 ft height, using a 20.5 inch wide roll and 33 ft roll length with a 21 inch pattern repeat, yields 7 strips. The adjusted strip length is 10.5 ft, so each roll provides 3 strips. The result is 3 rolls needed with an effective coverage of about 44 sq ft per roll.

FAQs

What if the pattern repeat is listed in centimeters?

Switch to metric units and enter the repeat in millimeters or centimeters as appropriate.

Do I need extra for trimming top and bottom?

The repeat rounding adds extra length. Add a small buffer if your walls are uneven.

What about half-drop patterns?

Half-drop patterns often increase waste. Use the listed repeat and expect higher roll counts.

Should I buy an extra roll?

Yes, especially for unique or discontinued patterns, repairs, or future changes.

Can I use this for multiple walls?

Yes. Sum the widths or calculate each wall separately and add the roll totals.

How it works

This tool models pattern repeat waste by rounding strip length up to the next repeat, then computes strips per roll and roll count. All calculations run client-side.

Disclaimer

Results are estimates. Always verify roll specifications and pattern match instructions from the manufacturer.