How many coats of paint do I need?

For walls in good condition with the same colour: 1 coat. For colour change or highly absorbent walls: 2 coats. For dark over light or vice versa: 2–3 coats + primer.

What is the coverage of interior emulsion paint?

Interior emulsion typically covers 12–14 m²/L per coat. Exterior or textured paint covers less, around 8–10 m²/L.

How is paint calculated for ceilings?

Measure length × width of the ceiling in metres. Apply the paint coverage (10–14 m²/L) and number of coats. For textured ceilings, use 20 % more paint.

Wallpaper Calculator

Last updated: 2026-06-23

Use the Wallpaper Calculator to get instant, accurate results. Enter your values below.

Inputs

Result

Enter values and press Calculate

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Common Sizes — Click to Fill

Room perimeter (m)	Wall height (m)	Roll length (m)	Roll width (m)	Pattern repeat (cm)
12 m	2.5 m	10 m	0.53 m	0 cm
14 m	2.5 m	10 m	0.53 m	0 cm
16 m	2.5 m	10 m	0.53 m	0.64 cm
18 m	2.7 m	10 m	0.53 m	0.64 cm
22 m	2.7 m	10 m	0.53 m	1.28 cm

What is the Wallpaper Calculator?

Wallpaper is one of the trickiest materials to estimate because pattern repeats create a lot of waste — a 60 cm repeat can add 20–30% to your material needs. This calculator converts your room dimensions and roll specs into the exact number of rolls to buy, accounting for both pattern repeat and the number of usable strips per roll.

You may also find the Paint Coverage Calculator, Carpet Calculator, and Crown Molding Calculator useful.

Who Uses This Calculator?

This tool is used by homeowners wallpapering a room, interior designers specifying feature walls, and decorators quoting renovation jobs.

How to Use the Wallpaper Calculator

Enter your Room perimeter.
Enter your Wall height.
Enter your Roll length.
Enter your Roll width.
Enter your Pattern repeat.
Click Calculate to see your results instantly.

Formula

The calculator uses the following formula:

Wall area = perimeter × height; Strips per roll = floor(roll_length ÷ (height + pattern_repeat)); Rolls = ceil(perimeter ÷ roll_width × strips_ratio)

Worked Example

A room with 14 m of wallpaperable perimeter, 2.5 m walls, using rolls that are 10 m long × 0.52 m wide with a 64 cm pattern repeat needs 11 rolls.

Step-by-Step Calculation

Wall area: 16 m × 2.5 m = 40 m²
Usable strips per roll: floor(10 ÷ (2.5 + 0.64)) = floor(10 ÷ 3.14) = 3 strips
Total strips needed: ceil(16 ÷ 0.53) = 31 strips
Rolls needed: ceil(31 ÷ 3) = 11 rolls

Common Mistakes to Avoid

Ignoring the pattern repeat — a 64 cm repeat can waste an entire strip per roll
Buying based on wall area alone without factoring in usable strips per roll
Not buying extra for patching future damage (keep 1 roll in reserve)

Pro Tip: Buy all rolls from the same batch number — the number printed on the label. Different batches can have subtle colour differences that are invisible in-store but obvious on the wall.

Frequently Asked Questions

How do I calculate wallpaper for a room with a pattern repeat?

Each strip must be cut so the pattern aligns at eye level. This wastes the top or bottom of each strip. The usable length per strip = roll_length ÷ (ceiling_height + pattern_repeat). The calculator does this automatically.

What is a full drop versus half drop wallpaper pattern?

A straight (full) drop means every strip starts at the same point in the pattern. A half drop means alternate strips are offset by half the repeat height. Half drop patterns generate more waste and need more rolls.

How wide are standard wallpaper rolls?

Standard UK/European rolls are 52–53 cm wide. US rolls are typically 68 cm wide. Some designers offer 70–90 cm wide rolls. Always measure and enter the actual roll width — do not assume.

Can I wallpaper over existing wallpaper?

Not recommended. Old wallpaper may bubble or peel when new paste is applied, and the added weight can cause both layers to fall. Strip the old paper first for best results.

How long does wallpaper paste need to soak?

Most paste manufacturers recommend 3–5 minutes of soaking time on the pasted strip before hanging. Thicker wallpapers or those printed on non-woven backing may need longer. Over-soaking causes stretching.

Written and reviewed by the CalcToWork editorial team. Last updated: 2026-06-23.