How many sheets of plasterboard do I need?

Work out the wall and ceiling area, then divide by the area of one sheet and add a waste allowance for cuts around windows, doors, and corners. The calculator does this from the room size and sheet size you enter.

What size are plasterboard sheets in NZ?

Common sizes are 2.4 by 1.2 metres, which is 2.88 square metres, and longer 3.0 or 3.6 metre sheets. Longer sheets mean fewer joints. The calculator lets you set the sheet size you are using.

Should I include the ceiling?

If you are lining the ceiling as well, include it. The calculator adds the ceiling area, which is the room length times the width, to the wall area. Untick the ceiling option if you only need the walls.

Plasterboard Calculator

This calculator works out how many sheets of plasterboard, often called Gib after the common NZ brand, you need to line a room, so you can order the right amount before the job starts. You enter the room length and width, the wall height, whether you are lining the ceiling as well as the walls, the sheet size you plan to use, and a waste percentage to cover cuts around windows, doors and corners. From these figures it works out the total wall area from the room perimeter times the height, adds the ceiling area if that box is ticked, then divides the total by your sheet size after applying the waste allowance. The result is rounded up to a whole number of sheets, because you cannot buy part of one, and the tool also shows the total lining area in square metres so you can sense check the number against a quote. It suits a single bedroom, a whole renovation, or a new build, and works with the standard 2.4 by 1.2 metre sheet or longer lengths if you want fewer joints. Because real rooms have alcoves, wardrobes and odd angles that a simple length and width cannot capture, treat the figure as a solid estimate for budgeting and ordering rather than an exact cutting list, and keep a couple of spare sheets on hand for mistakes.

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Room length (m)

Room width (m)

Wall height (m)

Sheet size (m²)

Waste

Include ceiling

0 sheets

plasterboard to buy

Lining area0 m²

How it works

The wall area is the perimeter, twice the length plus twice the width, times the height. If you line the ceiling, the length times the width is added. The total is divided by the sheet area, plus a waste allowance, and rounded up to whole sheets.

Worked example

A 4 by 3.5 metre room, 2.4 metres high, has about 36 square metres of wall, plus 14 square metres of ceiling, which is 50 square metres. With 2.88 square metre sheets and 10% waste, that is about 20 sheets.

Related calculators

Paint Calculator: paint for the walls.
Insulation Calculator: insulation packs.
Square Metre Calculator: work out an area.
Wallpaper Calculator: rolls of wallpaper.

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