Wallpaper Calculator

Wallcovering Installers Association (WIA) Estimating Standards

Professional paperhangers calculate material requirements using the Strip (Drop) Method rather than basic square footage because pattern repeats dictate cutting waste.

Primary Wallpaper Formulas

• Strip Width (Feet): W_strip = Roll Width (inches)12

• Total Required Strips: N_strips = Wall Width (ft)W_strip

• Cut Length Per Strip: L_cut (in) = (H_wall (ft) × 12) + 4"_trim + R_pattern repeat (in)

• Usable Strips Per Roll: N_strips/roll = Roll Length (in)L_cut (in)

• Total Rolls Required: Rolls = N_stripsN_strips/roll

Standard Roll Dimensions

• US Double Roll: 20.5" × 33 ft = 56.4 sq ft

• Euro Metric Roll: 20.9" × 33 ft (53 cm × 10.05 m) = 57.8 sq ft

• US Single Roll: 20.5" × 16.5 ft = 28.2 sq ft

How to Use This Calculator

Enter your Total Wall Width / Room Perimeter (Feet) (e.g. 28.0 in ft), Wall / Ceiling Height (Feet) (e.g. 8.5 in ft), Wallpaper Roll Format — choose from Standard US Double Roll (20.5" × 33 ft / 56.4 sq ft), Euro Metric Roll (20.9" × 33 ft / 57.8 sq ft), Single Roll (20.5" × 16.5 ft / 28.2 sq ft), Pattern Repeat Match (Inches) (e.g. 12.0 in in), and Windows & Doors Deduction (Sq Ft) (e.g. 40.0 in sq ft). Measure twice before entering dimensions — small measurement errors scale up significantly in material estimates.

The Formula

Conversion factors (to SI base unit or reference unit):

widthIn: 20.5

lengthFt: 33.0

Worked Example

Covering a 28-foot wall with an 8.5-foot ceiling and a 12-inch pattern repeat requires 17 vertical drops; since each 33-foot double roll yields 3 usable drops, exactly 6 double rolls are required.

Understanding Your Result

Construction estimates are starting points — site conditions, material specifications, and local code requirements will affect final quantities and costs. Always obtain at least three contractor bids for major projects. Local building departments can confirm permit requirements and inspection milestones. Add waste factors appropriate to the material type and complexity: 10% for simple rectangular shapes, 15–20% for complex geometries or custom cuts.