How do you find sq ft of a room you want to have painted like 28 by 56 house with 8 ft ceilings I know it is1344 but do you double it plus add for ceilings

I am assuming you mean to paint the room, not fill it with paint, correct?
If so, you do not need the cubed foot measurements of the room, but rather the surface area that you need to cover.

Do you mean that the room is measured 28 feet wide x 26 feet long? And it is eight feet tall?
If so, (assuming it is a regular rectangle room) you would multiply 8ft x 28ft, which is 244, and 8ft x 56 ft, which is 448. You add them together, and get 692 sq ft. You then multiply that by two, because you have so far only calculate two walls and need the others.

You get 1384 sq ft.

You only need to calculate the surface area of the ceiling if you are intending to paint it. If you have a flat ceiling, then it will be 1568. If your ceiling is slanted, then you need to measure the ceiling (as it will be longer) or find the angle, and use SohCahToa to find the length.
Assuming a flat ceiling, and you want to paint it also, then your grand total will be a surface area of 2952 sq feet to be painted.

(Anyone want to check my math? That number doesn't seem right, but I did it 2 times)

Of course, I was just speculating on what you were asking, since you didn't word it clearly. If you want something else, could you please ask?

Each room/area of house should be measured individually. The totals from each room/area added together. This will give u total area to be painted.

In each room/area, measure length of each wall, add together and multiply by height of wall. This will give area of walls.

Multiply length of one wall by length of perpendicular wall. This will give u area of ceiling.

Add area of walls to area of ceiling. This will give u area of room/area to be painted.

After getting total of all rooms/areas, add these numbers together. This will give u total of all rooms/areas to be painted.

This does not take into consideration any trim, doors or windows.

Chuck

hello:
if you want to to figure sq ft of walls you measure length x width
example : if a wall is 10 ft long and 8 ft high it is 80 sq ft, ceilings are measured the same or you can just meausure the floors example: if a room is 12x12 it is 144 sq ft so that is what the square footage on you're ceiling.


Hope fully my answer helps