# Wallpaper Calculator: Rolls from Drops, Height and Pattern Repeat

> Wallpaper is estimated in drops, not by area. Each drop is the wall height plus one pattern repeat and a trimming allowance. A roll yields as many whole drops as fit in its length, the walls need their net width divided by the roll width, rounded up, and the rolls are the drops needed divided by drops per roll, rounded up.

## What it calculates

For the walls of a room covered in wallpaper or vinyl wallcovering, the calculator gives:

- the **drop length**, with pattern repeat and trim;
- the number of **drops** each roll yields, and the length left over;
- the number of **drops needed** for the net wall width;
- the **rolls to order**, before and after a spare allowance.

## Inputs

**Total width of walls to cover** is in metres: the room perimeter, or the walls being
papered added together. The equivalent in feet is shown under the field.

**Wall height** is from the skirting to the ceiling or cornice.

**Width of openings to deduct** is the total width of doors and other full-height openings.

**Pattern repeat** is in centimetres, from the roll label; 0 for a plain or free-match
paper.

The **assumptions** panel holds the roll width and length, the trim allowance per drop and
the wastage and spare allowance.

## Method

1. Net width = wall width − openings.
2. Drop length = wall height + pattern repeat + trim.
3. Drops per roll = roll length ÷ drop length, rounded down.
4. Drops needed = net width ÷ roll width, rounded up.
5. Rolls = drops needed ÷ drops per roll, rounded up.
6. Rolls to order = rolls × (1 + allowance), rounded up.

Finished wallpapers and wall vinyls in roll form are specified under **EN 233**, and heavy
duty wallcoverings under **EN 259-1**. The roll size is on the label or data sheet.

## Assumptions

| Assumption | Default | Notes |
| --- | --- | --- |
| Roll width | 0.53 m | Common standard roll; replace with your product's data sheet |
| Roll length | 10.05 m | Common standard roll; wide-width commercial rolls differ |
| Pattern repeat | 32 cm | Illustrative; from the roll label |
| Trim per drop | 10 cm | Total for top and bottom |
| Wastage and spare rolls | 5% | Damage, mistakes and same-batch spares |

## Limitations

- **Openings are deducted by width only.** Paper above and below windows and over doors
  is counted as full drops, which slightly overstates the need.
- **Leftover lengths are not reused.** Short pieces can sometimes fill over doors or under
  windows; the calculator does not count them.
- **Half-drop and offset matches** can waste more than a straight match on some walls. The
  drop method with one full repeat per drop usually covers them, but check the label.
- **Sloping ceilings, stairwells and feature walls** need drops of different lengths;
  calculate each wall separately.
- **Adhesive, lining paper and wall preparation** follow the product's data sheet and are
  not counted.

## Worked example

Walls 18 m wide in total, 2.7 m high (8.9 ft), one 0.9 m door, 0.53 × 10.05 m rolls with a
32 cm pattern repeat, 10 cm trim and a 5% allowance:

| Step | Calculation | Result |
| --- | --- | --- |
| Net width | 18 − 0.9 | 17.1 m |
| Drop length | 2.7 + 0.32 + 0.10 | 3.12 m |
| Drops per roll | 10.05 ÷ 3.12, rounded down | 3 |
| Drops needed | 17.1 ÷ 0.53 = 32.26, rounded up | 33 |
| Rolls | 33 ÷ 3 | 11 |
| Rolls to order | 11 × 1.05 = 11.55, rounded up | 12 |

The room needs **11 rolls, so order 12** from one batch. Each roll leaves 0.69 m over after
three drops. The net wall area is 46.2 m² (497 sq ft), which by area alone would suggest only
9 rolls. With a plain paper the drop falls to 2.8 m but a roll still yields only 3 drops, so
the count does not change; at a 3.0 m wall height with the same repeat, only 2 drops fit in
a roll and the order rises to 18.

## How engineers use it

On a fit-out, wallcoverings are scheduled on the finishes layout by wall, with the product,
roll size, repeat and match. The installer works out drops wall by wall from the drawings,
plans where the pattern starts so it is centred on feature walls, and orders whole rolls
from a single batch with a few spares kept on site for repairs.

## When a professional design must replace it

Use the calculator to estimate rolls for a simple room or check a supplier's figure.
Replace it with a wall-by-wall take-off from the installer before ordering, and wherever
the wallcovering has a large or offset repeat, is a wide-width commercial product, covers
tall or irregular walls, or must meet a reaction-to-fire class set by the project's fire
strategy. That class comes from the product's test classification and the designer, not
from this calculation.

## Frequently asked questions

### How many rolls of wallpaper do I need?

Work out the drops: wall height plus pattern repeat plus trim. Divide the roll length by the drop length, rounding down, for drops per roll. Divide the net wall width by the roll width, rounding up, for drops needed, then divide by drops per roll and round up. 18 m of wall, 2.7 m high, less a 0.9 m door, in 0.53 × 10.05 m rolls with a 32 cm repeat needs 11 rolls, or 12 with a 5% allowance.

### Why not divide the wall area by the area of a roll?

Because the leftover at the end of each roll is too short for another full drop and is wasted. In the default example, 46.2 m² of wall divided by 5.33 m² a roll suggests 9 rolls, but only 3 drops of 3.12 m fit in each 10.05 m roll, so 11 rolls are needed before any spare allowance.

### How does the pattern repeat change the number of rolls?

Each drop is lengthened by one repeat so the pattern lines up with the next drop. When that pushes the drop past a third or a half of the roll length, a roll yields one drop fewer. At a 3.0 m wall height with a 32 cm repeat, the drop is 3.42 m, only 2 fit in a roll, and the default walls need 17 rolls instead of 11.

### Should I deduct windows from the wall width?

Deduct doors and other full-height openings. Paper is still needed above and below a window, and cutting round it uses most of a drop, so many estimators deduct little or nothing for windows. The calculator deducts only the total width you enter.

### What about wide-width commercial wallcoverings?

Commercial vinyl wallcoverings are often made in wider, longer rolls than the 0.53 × 10.05 m standard roll, and some are sold by the running metre. The same drop method applies: enter the roll width and length from the product data sheet.

### Why order spare rolls?

Rolls printed in different production batches can differ slightly in shade, so all rolls on a wall should come from one batch. A spare roll or two from the same batch covers damage during hanging and later repairs. The default allowance is 5%.

## Sources

- [EN 233](https://standards.cencenelec.eu/ords/f?p=CEN:105) — Wallcoverings in roll form — specification for finished wallpapers, wall vinyls and plastics wallcoverings
- [EN 259-1](https://standards.cencenelec.eu/ords/f?p=CEN:105) — Wallcoverings in roll form — heavy duty wallcoverings — specifications

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Source: https://hagerstone.com/calculators/wallpaper-calculator