Wallpaper Calculator: How Many Rolls?

How much wallpaper do I need?

Measure wall widths and use the greatest height where the ceiling or floor varies. Enter the actual roll length and width from the label. The calculator estimates free-match or straight-match paper for walls of one height, including a trimming allowance at the top and bottom of every drop.

For different wall heights, calculate each group separately. Drop-match papers, murals, stairwells and unusually shaped spaces need an individual layout. Use the result as a planning estimate and confirm it with your installer or supplier before ordering.

The wallpaper roll calculator formula

1. Drops required: divide the combined wall width by the roll width, then round up.
2. Cut length: add the trimming allowance to the wall height.
3. Straight-match adjustment: round that cut length up to the next whole pattern repeat.
4. Drops per roll: divide roll length by adjusted cut length, then round down.
5. Rolls required: divide drops required by drops per roll and round up.

For separate walls, rounding each wall's drop count up is a cautious approach when offcuts cannot be used elsewhere. A site layout can make more efficient use of some pieces, but do not count on that until the pattern and corners have been planned.

Worked example: a 4 metre wall

Imagine a wall 4 m wide and 2.4 m high. The chosen roll is 0.53 m wide and 10 m long. Allow 0.10 m in total for trimming each drop. These are example measurements, not the dimensions of every wallpaper roll.

• 4 ÷ 0.53 = 7.55, so you need 8 drops.
• For free-match paper, each cut is 2.50 m long.
• A 10 m roll supplies 4 full drops.
• 8 drops ÷ 4 = 2 rolls before any spare-roll allowance.

Now give the paper a 0.64 m straight repeat. The 2.50 m cut rounds up to 2.56 m. Only 3 full drops fit a 10 m roll, so 8 drops need 3 rolls. Pattern matching changes the answer even though the wall area stays the same.

Windows, doors and useful offcuts

Do not simply subtract the area of every opening. You may still need full-length drops beside the opening, with matching pieces above or below it. An offcut is useful only if its width, length and pattern position fit the next location.

For an initial order estimate, leaving openings in the wall dimensions is a conservative starting point. For large openings or several walls, ask for a measured layout so the calculation reflects the actual hanging pattern.

Mark window and door positions on a sketch. Include returns, alcoves, chimney breasts and any sections that extend above a door or below a window.

To check a material budget, multiply the calculated rolls by the price you enter. For a two-roll estimate, double your supplier's price per roll to obtain the paper total. Add your chosen spare rolls before comparing the total; labour and preparation are separate.

Pattern repeat is not the whole match instruction

A straight match repeats at the same vertical level on neighbouring drops. A half-drop or other offset match shifts that alignment. It can need alternating cut lengths or a different roll plan, so this calculator does not claim to price or optimise those layouts.

Read our wallpaper pattern matching guide and keep a photograph of the full roll label. Note any reverse-hanging, paste or soaking instructions as well as the repeat.

Before you order

• Confirm roll width and length for the exact product.
• Check the repeat and match type.
• Measure the highest point and every included wall.
• Confirm batch numbers for a consistent appearance.
• Discuss spare material for damage or later repairs.
• Check delivery timing and the supplier's return conditions.

For the complete sequence, use our wallpaper guide. If old paper is still in place, allow for removal and preparation before final hanging arrangements are made.

Your questions