Ceiling Area
Free Ceiling Area calculator with clear step-by-step results.
About Ceiling Area
A flat ceiling matches the floor footprint, but a sloped or coffered one has more surface than the plan suggests - a 25 degree pitch adds about 10%. The waste allowance covers offcuts around light fittings and the paint figure assumes two coats at the coverage rate you enter.
Formulas
Sloped surface
Surface = length x width / cos(pitch angle)
Paint required
Litres = surface x (1 + waste) x 2 coats / coverage per litre
Worked example
With the default values below, Ceiling Area returns Ceiling surface area of 20.80. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Room lengthminimum 0.1 m
- 5.2 m
- Room widthminimum 0.1 m
- 4 m
- Ceiling typeone of Flat, Sloped / cathedral (25 degrees), Coffered or tray (extra surface)
- Flat
- Cutting and waste allowanceaccepts 0–40 %
- 10 %
- Paint coverageminimum 1 m2/L
- 11 m2/L
Results
- Ceiling surface area
- 20.80 m2
- Floor footprint
- 20.80 m2
- Area to order including waste
- 22.88 m2
- Paint for two coats
- 4.16 L
Step by step
- 1Values used
- 2Sloped surface
- 3Paint required
- 4Ceiling surface area= 20.80 m2
- 5Floor footprint= 20.80 m2
- 6Area to order including waste= 22.88 m2
- 7Paint for two coats= 4.16 L
Assumptions and limits
- The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
Do I subtract light fittings and vents?
No. Recessed fittings are small relative to the ceiling and you still need material around them, which is what the waste allowance covers.
Why does coffered add 18%?
The drops and returns of each recess create vertical surface that does not appear on plan. Eighteen percent is a working average; measure the reveals for an exact figure.