Painting - calculating the cost of painting

I would like to know how to calculate the cost of painting a house; if it's the entire exterior, the garage, or just the rooms. How would I do it because I would like to know how much one will charge me by sq. footage per room or complete footage of the house.

It will vary from one part of the country to another. It might be best to ask your friends for recommendations and get three quotes. It would give you some ideas and prices to compare.

The interior will be by square footage of walls and ceilings if that is what you want painted. The trim will probably be by the running foot. Doors are usually per each. Outside one price for all, but usually available for just the siding and just the trim.

Other variables include: repairs, washing, caulking, priming, multiple stories, multiple colors, stairways, vaulted ceilings.

Hope this helps.

The prep work is everything. Even a lower quality paint can look good and last with first class prep work. Walls should be washed before painting. Even outside surfaces need to be cleaned.
If you get bids be sure to specify the paint you like. I watched a larger local painting company buy many gallons of Sherwin Williams' cheapest paint for his jobs. I would never hire them after seeing that. Most of the bill is labor. Use the best paint you can get.