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.
"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."