Wallpaper Calculator

Calculate how many rolls of wallpaper you need for a room, accounting for doors, windows, pattern repeats, and paste.

Walls (L × H)

#1×ft

#2×ft

#3×ft

#4×ft

Doors (qty)

21 sqft each

Windows (qty)

15 sqft each

Roll Width

Roll Length

Pattern Repeat

Wallpaper Grade

Rolls Needed

7 rolls

345 sqft net wall area · ~$350 est. cost

Gross wall area	396 sqft
Deductions (1D + 2W)	−51 sqft
Net wall area	345 sqft
Roll coverage	56.4 sqft/roll
Rolls needed	7
Paste	4 gal
Primer/sizing	2 gal

Wallpaper (7 rolls @ $30)	~$210
Paste (4 gal @ $20)	~$80
Primer (2 gal @ $30)	~$60
Total materials	~$350

info

Mike Callahan:Always order 2 extra rolls from the same dye lot. Wallpaper dye lots vary — if you come back for one more roll in 3 months, it won’t match. Two extra rolls is cheap insurance.

Methodology

Gross wall area = sum of each wall’s length × height. Deductions: doors at 21 sqft each (3×7 ft), windows at 15 sqft each (3×5 ft). Roll coverage = (roll width ÷ 12) × roll length in sqft. Pattern repeat reduces usable coverage by 20% to account for alignment waste. Rolls needed = ceil(net area ÷ effective roll area). Paste at 1 gallon per 100 sqft, primer/sizing at 1 gallon per 300 sqft. Costs are material only and do not include installation labor. Prices reflect 2026 averages.

Frequently Asked Questions

How many rolls of wallpaper do I need for a room?

Measure each wall (length × height), add them up for total wall area, then subtract doors (21 sqft each) and windows (15 sqft each). Divide the net area by the usable coverage per roll. A standard American single roll (20.5” wide × 33 ft long) covers about 56 sqft, but usable coverage drops to about 45 sqft after trimming and matching. For a typical 12×10 room with 9-ft ceilings, 1 door, and 2 windows: gross area = 396 sqft, net = 345 sqft, needing about 7–8 single rolls.

What is a pattern repeat?

A pattern repeat is the vertical distance between identical points in a wallpaper’s design. If the pattern repeat is 24 inches, the design repeats every 24 inches. When hanging, you must align strips so the pattern matches at seams, which means cutting off and wasting material at the top and bottom of each strip. Larger pattern repeats generate more waste — a 24” repeat can waste 10–15% more wallpaper than a pattern-free design. This calculator adds 20% waste for any pattern repeat.

Do I need to size (prime) the walls before wallpapering?

Yes. Wall sizing (also called wallpaper primer) seals the wall surface, prevents the paste from soaking into drywall, makes hanging easier by letting you slide strips into position, and — critically — makes future removal much easier. On new drywall, sizing is essential. On previously painted walls, it’s strongly recommended. Use a dedicated wallpaper primer/sizing product, not regular latex primer. One coat is typically sufficient at about 300 sqft per gallon.

How do I handle outlets and switches?

Turn off the circuit breaker first. Remove the cover plates before hanging. Hang the wallpaper strip right over the outlet/switch box, then use a utility knife to cut a small X from corner to corner of the box. Fold the flaps through the opening and trim flush with the edge of the box. Replace the cover plate over the wallpaper. For a cleaner look, some installers trim the wallpaper to sit just inside the cover plate edges so no paper shows. The small cutouts do not meaningfully affect roll counts.

Roll counts based on net wall area divided by usable roll coverage. Pattern repeat reduces effective coverage by 20%. Door and window deductions use standard sizes (3×7 ft door, 3×5 ft window) — measure actual openings for precision quotes. Always order 1–2 extra rolls from the same dye lot for repairs and matching. Costs are material only.