Measuring walls and estimating wallpaper

01Measure the walls

1. 1.Measure the width of each wall at roughly waist height, corner to corner. Write each wall down separately.
2. 2.Measure the height from the top of the baseboard to the ceiling (or to the crown molding) in at least two places. Use the largest figure; old houses are rarely level.
3. 3.Measure every door, window and built-in on the papered walls: width and height.
4. 4.Note the roll width, roll length, pattern repeat and match type from the paper you plan to buy. These change the answer more than the wall size does.

TipMeasure in one unit only (inches or centimeters) and convert the roll length to the same unit before calculating.

02Think in drops, not square footage

Wallpaper is hung in full-height strips called drops. Dividing wall area by roll area underestimates, because each drop is cut longer than the wall and the leftover end of a roll is usually too short to use.

1. 1.Drops per wall = wall width ÷ roll width, rounded up.
2. 2.Cut length = wall height + trimming allowance (about 4 in / 10 cm in total), rounded up to the next whole pattern repeat.
3. 3.For a half-drop match, add half a repeat to every cut on average.
4. 4.Drops per roll = roll length ÷ cut length, rounded down.
5. 5.Rolls = total drops ÷ drops per roll, rounded up.

03Doors, windows and spare rolls

• —Only subtract a drop for each full roll width a door or window spans. Paper is still needed above and below openings.
• —Add 10–15% for mistakes, awkward corners and future repairs. Complex rooms (dormers, many openings, stair walls) need more.
• —Buy every roll in one order and check that the batch or lot number matches. Colors can vary between print runs.
• —Treat any calculation, including ours, as an estimate. Confirm quantities with your supplier or installer before ordering.