Wallpaper Calculator

How to Use This Wallpaper Calculator

Getting the right amount of wallpaper is crucial—too little means a mid-project trip to the store (risking mismatched dye lots), and too much wastes money. This calculator accounts for room dimensions, openings, and pattern waste to give you an accurate roll count.

1. Enter your room dimensions. Measure the length and width of the room in feet. For wall height, measure from floor to ceiling (standard is 8 feet, but verify yours).
2. Count windows and doors. Standard windows are calculated at 15 sq ft and doors at 21 sq ft. For unusually large openings, you may want to measure precisely and adjust.
3. Check your wallpaper roll specifications. Most American rolls are 20.5 inches wide and 33 feet long, but European rolls differ. Check the packaging.
4. Enter the pattern repeat. This is critical for patterned wallpaper. Look on the label for "pattern repeat" measured in inches. Solid colors and textures use 0.
5. Review your results. The calculator adds a 10% waste buffer. For complex rooms or large patterns, consider adding an extra roll beyond the recommendation.

Remember: it's always better to have an extra roll than to run short mid-project.

How It Works

Measuring for Wallpaper

Wallpaper estimation starts with calculating the total wall surface area. This is the room's perimeter (the sum of all wall lengths) multiplied by the wall height. A 12×10 foot room has a perimeter of 44 feet; at 8 feet tall, that's 352 square feet of wall space before subtracting openings.

Windows and doors are subtracted because you won't wallpaper over them. Standard estimates are 15 square feet per window and 21 square feet per door. For precision work, measure your actual openings, but these averages work well for planning.

Understanding Pattern Repeats

Pattern repeat is the distance before a wallpaper design repeats vertically. A 21-inch repeat means the pattern cycles every 21 inches. When hanging wallpaper, you must align these patterns horizontally across strips, which requires cutting extra paper to position the pattern correctly.

For example, with an 8-foot (96-inch) wall and a 21-inch repeat, each strip needs the 96 inches of usable paper plus up to 21 inches of waste to align the pattern. This significantly reduces how many usable strips you get per roll.

Why Pattern Repeats Increase Waste

Larger pattern repeats mean more waste per strip. A 0-inch repeat (solid or texture) has almost no pattern waste—you can start each strip wherever you want. A 24-inch repeat might waste an entire pattern length per strip as you align it with the previous strip. This is why patterned wallpaper projects need 15-30% more rolls than solid colors for the same room.

Examples

Example 1: Small Bathroom (5×8 ft)

A powder room with minimal openings:

• Room: 5 ft × 8 ft, 8 ft ceiling
• 1 door, 0 windows (interior bathroom)
• Standard roll (20.5" × 33'), no pattern

Calculation: Perimeter = 26 ft × 8 ft = 208 sq ft total. Minus door (21 sq ft) = 187 sq ft net. At ~56 sq ft usable per roll with no pattern waste, you need approximately 4 rolls.

Example 2: Bedroom (12×14 ft)

A standard bedroom with windows:

• Room: 12 ft × 14 ft, 8 ft ceiling
• 1 door, 2 windows
• Standard roll, no pattern

Calculation: Perimeter = 52 ft × 8 ft = 416 sq ft. Minus openings (21 + 30 = 51 sq ft) = 365 sq ft net. You need approximately 8 rolls.

Example 3: Living Room with Pattern (16×20 ft)

A larger room with patterned wallpaper:

• Room: 16 ft × 20 ft, 9 ft ceiling
• 2 doors, 3 windows
• Standard roll with 21-inch pattern repeat

Calculation: Perimeter = 72 ft × 9 ft = 648 sq ft. Minus openings (42 + 45 = 87 sq ft) = 561 sq ft net. With the 21-inch repeat reducing usable area per roll, you need approximately 16-18 rolls—nearly double what you'd need for a solid color.