Do I subtract windows and doors when measuring for wallpaper?

No. Measure the full wall and note each opening separately with its position and size. A proper calculation subtracts openings strip by strip, which you cannot do by hand reliably. Wallsizer does this automatically.

Do I include the skirting board in the wall height?

Yes, the wall height stays floor to ceiling so that window sills and every other measurement share one zero line. The skirting itself is entered separately, in the Wainscoting / skirting field, measured from the floor to its top edge. The covering is then calculated only for the band above it.

Where do I measure a window from?

From the left corner of the wall the window sits on, to the left edge of the window frame. Then note the window width and height including the frame, and the sill height measured from the floor.

What if the wall height is different in different spots?

Rooms are never perfect. Measure the height in two or three places and use the largest number. It is always safer for the covering to run slightly long than to come up short.

How do I measure an attic room with sloped walls?

Measure each sloped wall at both ends: the height where the wall is tallest and the height where it is shortest. In Wallsizer, turn on Sloped walls and enter the left and right heights.

Should I measure in centimeters or inches?

Either works, just never mix them in one project. Wallsizer accepts centimeters, decimal inches and feet and inches, including fractions like 9 feet 6 1/2 inches.

Measuring guide

Measure the room.
We do the math.

Fifteen minutes with a tape measure is all a room needs. This guide shows exactly which numbers to write down for wallpaper or a wall mural, and where each one comes from. You never subtract, convert or estimate anything yourself: enter the raw measurements in Wallsizer and the quantities, the drawing and the cut sheet follow.

You need a metal tape measure (cloth ones stretch), something to write on, and ideally a second pair of hands for wide walls. Measure everything in one unit, centimeters or inches, and never mix the two in one room.

The two rules that prevent every mistake

1. Everything starts at the floor and at the left corner

Every height is measured up from the floor. Every horizontal position is measured from the left corner of the wall you are standing in front of. One reference system, zero confusion on site.

2. Never subtract anything yourself

Do not deduct windows, doors or radiators, and do not add waste. Openings interact with strips and pattern repeats in ways a mental discount cannot capture. Write down the true numbers; the calculation removes exactly what can be removed, strip by strip.

Wall width

Stand in the room and pick a starting corner. Go around from left to right and measure each wall corner to corner, at about chest height. Write each wall down separately, in order: Wall A, Wall B, Wall C, Wall D. In Wallsizer the walls unfold left to right into one long elevation, and the total width adds itself up.

Each wall is its own measurement. The room unfolds into one line.

A wall means one flat surface. If the room has a chimney breast or an alcove, treat each flat face as its own wall and measure it separately.

Wall height

Measure from the floor to the ceiling. Do not stop at the skirting board (baseboard) and do not subtract it from the height: the floor is the zero line for everything, including window sills. The skirting gets its own field, covered two sections below. If the paper will stop under a cornice or crown molding, measure to the bottom edge of the molding instead of the ceiling.

Rooms are never perfect, so measure the height in two or three places along the wall and keep the largest number. Slightly long trims clean on site; short does not.

One zero line: the floor. The skirting stays inside the measurement.

Doors & windows

Openings are where hand calculations go wrong, so give each one four honest numbers and let the calculator do the rest. Every opening belongs to the wall it sits on. Measure the opening including its frame, since the covering stops at the frame, not inside it.

From left: from the left corner of that wall to the left edge of the frame.
Width: the opening across, frame included.
Height: the opening top to bottom, frame included.
Sill (windows and niches): from the floor up to the bottom of the opening. A door sits on the floor, so its sill is simply zero.

From left, width, height, sill. Frame included, floor as zero.

Small things on the wall, like sockets, switches, thermostats or a radiator, are not openings. Ignore them; the covering runs behind or around them.

Wainscoting & skirting

The covering usually stops above the floor: at the top of the skirting board, or at the rail of paneled wainscoting. Wallsizer has one field for this: Wainscoting / skirting, per wall, in the Walls tab.

The rule: measure from the floor up to where the covering will stop, and enter that number. Just a skirting, enter its height. Wainscoting, enter floor to the top of the rail. The wall height itself stays floor to ceiling, and the drawing hatches the uncovered band exactly as the installer will see it. If you skip the field, the order simply runs a little generous, never short.

One number per wall: floor to the top of the rail, or of the skirting.

Sloped walls

Attic rooms and dormers have walls whose top edge slopes. Measure the height of the wall at its left end and at its right end, both from the floor. In Wallsizer, switch Sloped walls on in the Walls tab and enter both numbers; the drawing and every strip length follow the slope.

Tallest end and shortest end. The slope between them is automatic.

Units

Work in whatever your tape shows: centimeters, decimal inches or feet and inches. Wallsizer switches between them with one click and accepts real-world entries like 290.5, 114.25 or 9'6 1/2. The only rule: one unit per project, never a mix.

The checklist

Width of every wall, corner to corner, left to right around the room.
Height floor to ceiling, measured in 2-3 spots, largest kept. Skirting included.
Every door and window: from left, width, height, sill. Frame included, sill from the floor.
Wainscoting / skirting per wall: floor to the top of the rail or of the skirting board, if present.
Sloped walls: left and right heights, both from the floor.
Nothing subtracted, nothing added. Raw numbers only.

Enter your numbers in Wallsizer Read the handbook

Common questions

Do I subtract windows and doors?

No. Openings interact with strips and pattern repeats, so a flat discount is wrong more often than it is right. Note each opening with its position and size; the calculation removes what can truly be removed, strip by strip.

Do I subtract the skirting board from the wall height?

No. The height stays floor to ceiling, so window sills and everything else share one zero line. The skirting goes in the Wainscoting / skirting field instead, and the quantities come out exact. If you skip the field, the order simply runs a little generous, never short.

Do I add extra for waste or trimming?

No. Trim allowances, pattern repeat waste and cutting margins are part of the calculation. Your job is only to measure what is really there.

The wall is 300 cm in one corner and 302 cm in the other. Which one?

The larger one. A covering that runs a touch long is trimmed on site in seconds; one that runs short is a reorder.

Is a chimney breast one wall or three?

Three: the front face and the two returns, each measured as its own flat wall. The same goes for alcoves.

What about radiators, sockets and light switches?

Ignore them. They are not openings; the covering runs behind or is cut around them during installation.

My tape shows feet and inches. Do I have to convert?

No. Switch Wallsizer to ft-in and type entries exactly like 9'6 1/2. Conversions are where errors sneak in, so let the app do them.

Measure the room.We do the math.