This is described in method one. If the ceiling is flat, by calculating the floor area, you now have your ceiling area as well. For rectangular and square rooms with flat ceilings, the area of the floor is the same as the ceiling’s area.If you have any extra parts of the ceiling that stick out or cave in, continue on to step two.
 This step only applies to ceilings that are not flat. Many ceilings also have alcoves and window bays that stick out; measure the width and depth of any alcoves or window bays.Record all measurements.


A ceiling that slopes or has recesses or variation of any kind will have a larger surface area than the floor, so keep that in mind when buying materials (i.e. buy a little extra).
Ceilings can be difficult to reach. If you are measuring a ceiling, ask a friend for assistance.
You will probably need a ladder to reach the ceiling for measurement.
 Add all additional measurements to the number calculated in step one. Write the total down.
 If you don’t have skylights on the ceiling, skip this step. Ceilings sometimes have skylights, and the area of these must be subtracted from the total ceiling area calculated in step three. Measure the length and width of a skylight to get its area. Then, multiple the length and the width. Now, you have the area of the skylight.
 Subtract the number calculated in step four from the total area of the ceiling. The result of this calculation is the square footage of your ceiling.
Calculate the floor area.
Measure any additions to the ceiling area separately.
Add extra ceiling measurements to the area of the room.
Measure the area of any skylights.
Subtract the area of the skylight from the ceiling area.
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