On average, expect to pay $0.60–$1.60 per square foot for exterior painting. The average for painting labor across the country is $30–$40 per hour before you pay for paint, painting supplies, location costs, and equipment. To get a very general estimate, though, painting contractors will take into account the square footage of your home and the number of stories and also factor in normal prep work.
An example of the wall measurement would be: 40 linear feet of bedroom space, x 8 wall height, =  320, x 2 = 640. Minus 1 door (60) and 2 windows (80) = 500 sq feet being painted. Then divide the 500 by 400 (sq feet per gallon), and you get 1.25 gallons (4.73 L) needed for that room. For this, you'd need 1 gallon (3.8 L) and 1 US-quart (950 ml). If the amount it comes out to is over 1.3, we recommend just getting 2 gallons (7.6 L) so that you have leftovers if needed, since 2 US quarts (2,000 ml) costs essentially the same as a gallon in most stores.
There are a few ways to prevent your interior house paint from fading — or stop it from getting worse. One simple fix is to install shades or curtains to block incoming sunlight. If you don’t want to shut out the light, you can also tint your windows with a UV protectant. However, fading shouldn’t be much of an issue if you use high-quality interior house paint.
Scale has one of the biggest impacts on deciding whether to hire painting help or take matters into your own hands. If you want to paint your home, consider whether or not this is a realistic task to take on yourself. For instance, is your house multiple stories or a townhouse? Do you just want to paint the kitchen or the entire exterior? Once you factor in the time it takes to do the prep work and lay down multiple coats of paint, a DIY paint job can get complicated. If the house painting job is extensive, you may want to leave it to professionals.
In addition, paint features such as mold and mildew resistance are important cost factors. Many mold-inhibiting bathroom paints, for instance, cost substantially more than ordinary latex-acrylic paint—sometimes close to twice the cost. Also, paints that come with warranties from the manufacturer may be more expensive depending on the length of the warranty. (A two-year warranty is standard.)
If the exterior of your home is unpainted or has been scraped and sanded, you will want to lay down a coat of primer. Make sure that the primer you’re using is right for the surface you’re painting. While most surfaces can be treated with acrylic primer, some surfaces, like cedar and redwood, require oil-based primers. The oil stops the wood tannins from bleeding through the topcoat.
Your homeowner’s association might limit you as to how unique you can be with your exterior paint choices. Check with them first to make sure you don’t have to redo your hot-pink-plus-unicorns murals. It can help to drive around your neighborhood to see what your neighbors have chosen and come up with a color scheme that fits in. If you’re not sure, stores can give you small cans of paint so you can paint patches of color in discrete parts of the exterior to see how they look before purchase.
For trim and doors, start with 1 gallon (3.8 L) of trim paint for every 600 sq feet of floor space. Purchase more at the store if/when needed. Trim is something that is difficult to calculate exactly, and it is more time-efficient to simply start with less than you need, and go buy more after you have used up the first round of paint and determined how much you will need to finish by seeing how much you have painted so far, compared to the gallons used.
After you have done the multiplication, subtract about 40 sq feet per window, and about 60 sq feet per door. Divide by 400 (interior paint covers 400 sq feet per gallon). The number that remains, is how many gallons you will need. If doing multiple wall colors, then you should do this process for each room (or sets of rooms) with a particular color. 
It’ll cost anywhere from $200 to $6,000 to hire a painter. Expect small jobs, like kitchen cabinets or trim, to run $200 to $2,000. Larger projects, like your home’s exterior, range from $1,000 to $6,000. To estimate your needs, figure paying $2 to $6 per square foot or $20 to $50 per hour. Actual costs vary considerably depending on coverage area, type of work and regional cost of living differences.
Homeowners report that painting a home’s exterior costs an average of $2,923 with a typical range between $1,734 and $4,119. The average price per square foot ranges from $0.50 to $3.50 depending on your location, condition of your exterior and accessibility. Stucco and brick cost an average of $1 per square foot more than vinyl or wood. The average 2,500 square feet home costs an average of $4,000, though it can range from $1,250 to $8,750.