Wallpaper Calculator

Wall width (ft). Measure the width of one wall or uninterrupted run that will receive full-height strips. Calculate separate walls individually when offcuts cannot be shared reliably. Doors and windows are not automatically deducted, because they may not save an entire strip.

Wall height (ft). Measure the greatest finished wall height for this run, from the intended top edge to the bottom edge of the covering. Trimming allowance is entered separately. A sloping ceiling or substantially different wall heights may need separate strip planning.

Roll width (in). Enter the usable width of the selected wallpaper roll. Dividing wall width by this dimension gives the number of full-width strips needed. Check the actual product rather than assuming a standard width.

Actual packaged roll length (ft). Enter the actual length in the packaged roll you are buying. Packaging described as a double roll may not match a single-roll pricing unit. Confirm the delivered length so the purchasing count refers to the correct package.

Total trimming allowance per strip (in). Enter the total extra length allowed for trimming both ends of each strip. If you need allowance at the top and bottom, add them together here. The calculator adds this once to the wall height before adjusting for pattern repeat.

Straight-match pattern repeat (in). For a straight-match pattern, enter the distance along the roll between matching points in the pattern. Strip length is rounded upward to a complete repeat so matching strips can be cut. Enter zero for no repeat; offset or half-drop patterns need a separate layout.

Allowance (%). Enter the percentage you want to add for cutting, handling loss or other conditions specific to this work. Apply it to the measured quantity rather than enlarging the measurements as well. The suggested value is editable, not a universal recommendation; enter zero when no allowance is needed.

Required strip cut length includes trimming and, when entered, a whole pattern-repeat allowance. Strips include the added allowance and are rounded to whole strips. Usable strips per roll counts only complete strips at that cut length; rolls then round the purchase upward. Do not substitute a rounded-down fractional reference when checking whether a strip fits.

Net strips = ceil(wall width ÷ roll width in matching units). Cut length = wall height + trimming, rounded upward to a whole pattern repeat when repeat > 0. Strips per roll = floor(roll length ÷ cut length). Apply waste to strip count and round up; rolls = ceil(required strips ÷ strips per roll).

Worked example: A 12 ft-wide × 8 ft-high wall, 24 in-wide × 33 ft packaged rolls, 4 in total trim and a 12 in repeat need 9 ft strips. Six net strips become seven with 10% waste. Three strips fit each roll, so buy 3 rolls.

One wall or uninterrupted run, full-height strips, random or straight-match patterns only. Windows and doors are not deducted because they may not save a full strip. Offset/half-drop matches, roll-end damage and special layouts need installer review.

Reference guidance

Wallcoverings Association estimating and pattern-repeat guidance. Consult the relevant product or estimating instructions. The illustrative numbers above are not specifications for the linked products.