Take for example, I charge 1.75 sq foot for 10x10 room with 8 foot ceilings. By my calculations this would cost $175 with floor space sq foot, but with you method, it would cost $576.00 That is outrageous. Of course I didn't subtract the windows and doors, which is another thing that makes no sense. Cutting in around those windows takes more time, then just rolling a wall.
I was a professional painter way way back for a company. Now I am dabbling in working around the neighborhood here and there and needed to know how much I should charge. I recently painted an entire home including woodwork / doors / windows/ baseboards and the paint costs $230 ish and I did it free for my best friend . It took me 4 days to do . 7am-9pm . It turned out absolutely beautiful , and every room was a different color .
Don't hesitate to ask all the questions you need to feel comfortable hiring a professional. You can also ask 3-4 professionals to make sure you have the right quote in mind. You must make sure they have a warranty or some kind of paperwork stipulating the quality of their jobs. Insurance is also a #1 priority to consider, as damage can happen in the process of painting.
Hired a pro to paint interior and exterior of my house. It was new construction. Outside is approx. 50% board and batten, also had cedar beams inside and out on porches. Outside was 3000 and inside was 8000. this included prime and paint all base, doors, closets and cabinets. All paint and stain was Sherwin Williams, high quality stuff. I highly recommend getting pros you dont have to bird dog and punch over and over! May cost a little more initially, but you'll be alot happier with the results!!
"Rafael was very professional, detail-oriented, pleasant to communicate with (responds promptly, returns calls, confirms appointments) and always showed up on time. He painted my daughter's room beautifully and for a reasonable price (offered pricing with and without paint). His work was precise and without mess. I will definitely hire him again for more painting projects."