Enrichment · Passion Projects · Home and garden

Count the strips,
not the square feet.

Type the walls, the height and the numbers on the roll label. The calculator counts strips the way paperhangers do, with the pattern repeat on every strip, so you buy enough from one batch.

Count the rollsWhat you get

The wallpaper calculator

The worked example is made up: four bedroom walls, 8 ft high, with a 21-inch pattern repeat. Nothing you type leaves this browser.

Loading the calculator. If nothing appears, turn on JavaScript.

What you get

Enrichment · Passion ProjectsFree

What you finish with
Rolls to buy, strips in all and per roll, each wall’s strip count and the wall area. It prints as a summary and downloads as a spreadsheet.
Who it is for
Families decorating a room, interior design and family and consumer sciences students, and anyone practising measurement.
Format
Browser calculator for a phone, tablet or computer, by touch or keyboard. Prints a summary; downloads a spreadsheet (.csv); export and import a file.
Access
Free. No account, no sign-in and nothing to install. Everything you type stays in this browser; nothing is sent to Caveat.
Where it lives
The Passion Projects space in Caveat Enrichment.
Support
Questions, a correction or a request: team@caveatacademic.com.

How to use it

  1. Measure each wall’s width and the wall height.
  2. Type the roll width, length and pattern repeat from the label.
  3. Keep a few inches of trim allowance.
  4. Choose whether to add a spare roll.
  5. Read the rolls and print the summary for the store.

Count the rolls

How the rolls are counted

Round down per roll, round up per wall.

The worked example: a bedroom with a 21-inch repeatStrip length121 in96 + 21 repeat + 4 trimStrips a roll3396 in ÷ 121, round downStrips needed288 + 6 + 8 + 6 by wallRolls10 + 1 spare28 ÷ 3, round upThe worked example: a bedroom with a 21-inch repeatStrip length121 in96 + 21 repeat + 4 trimStrips a roll3396 in ÷ 121, round downStrips needed288 + 6 + 8 + 6 by wallRolls10 + 1 spare28 ÷ 3, round up
Wallpaper is counted in strips, not square feet. A big repeat can cost a whole strip per roll, which is why area-only estimates come up short.

Why strips

Paper goes up in full-height strips, so the question is how many strips fit across each wall and how many come out of each roll. Strips across a wall round up, since a partial strip still needs a full one. Strips from a roll round down, since the last short piece cannot cover a wall. Dividing square feet by the roll’s area ignores both and usually comes up short.

Repeats and batches

A patterned paper must line up from strip to strip, so each strip uses its height plus up to one full repeat. A 21-inch repeat on an 8-foot wall turns four strips a roll into three. Rolls are printed in batches whose colours can differ slightly, so buy every roll, and a spare for repairs, with the same batch number.

Sources

  1. National Guild of Professional Paperhangers. Estimating wallcovering by strips (drops) and pattern match (ngpp.org).
  2. National Institute of Standards and Technology. Handbook 44, appendix C: the inch and the foot (nist.gov).
  3. National Council of Teachers of Mathematics. Measurement and rounding in context (nctm.org).
  4. U.S. Consumer Product Safety Commission. Ladder safety for home projects (cpsc.gov).

The worked example is made up. Check the manufacturer’s own coverage figures on the label. Your figures stay in this browser. Support: team@caveatacademic.com.