How much wastage should I allow?

Wastage covers cuts, breakages and the offcut at the end of every run. Ordering the exact computed quantity reliably means a second trip.

Construction & HomefinishingIndia only

False Ceiling Calculator

False ceiling boards and the grid to carry them. Board count is straightforward; the framing runs at roughly three to four metres of channel per square metre, which is the larger part of the cost.

Also called: gypsum ceiling calculator, pop ceiling quantity.

Boards

11.83

11.83 boards for 20 m² over 1 coat(s), including 10% wastage.

Area after deductions (m²)

Area across all coats (m²)

Before wastage

10.75

Area one unit covers (m²)

1.86

How this is calculated

Method and background

How this is calculated

Area divided by board coverage. The framing is the part worth planning: perimeter channel around the room, main channels at 1.2 metre centres and intermediate channels at 450mm produce roughly three and a half metres of section per square metre of ceiling, and the fixing accessories scale with it. Level and plumb matter more than quantity here, since a ceiling shows every deviation.

quantity = area * coats / coverage per unit, plus wastage

A: Net area (m2)
c: Coats (count)
r: Coverage per unit (m2)
s: Wastage (decimal)

Worked examples

Each of these is asserted on every build. If a change to the engine ever moved one of these answers, the build would fail before the page could print it.

a room ceiling

Length (m): 5
Width or height (m): 4
Or enter the area directly (m²): 0
Openings to deduct (m²): 0
Area one board covers (m²): 1.86
Coats or layers: 1
Wastage: 10%

Boards11.83

20 / 1.86, worked by hand

Open this example

entering the area directly

Length (m): 0
Width or height (m): 0
Or enter the area directly (m²): 30
Openings to deduct (m²): 0
Area one board covers (m²): 1.86
Coats or layers: 1
Wastage: 10%

Boards17.74

boundary: the override path

Open this example

Method and limits

What it assumes

A standard grid at 1200 by 450 centres.

What it deliberately does not model

Framing, screws and jointing compound are separate quantities.
Openings for lights and diffusers add cuts and therefore waste.

Formula version 1.0.0 · definition 1.0.0 · India · Report a problem with this calculator

Frequently asked questions

How much wastage should I allow?: Wastage covers cuts, breakages and the offcut at the end of every run. Ordering the exact computed quantity reliably means a second trip.