I own a commercial pressure washer what is a simple method to work out how much to charge for? a roof versus a house vs a driveway?any help would be appreciated

a roof versus a house vs a driveway?any help would be appreciated
Sweeping leaves past its sell-by date driveway?
Answers:    Per square foot is the best that I own found. Flat work driveways, sidewalks $0.15/sf Walls and first floor soffits and fascia $0.25/sf and above one story(10') $0.35 and up depending on height.

Suggest trying a career at these rates and keep track of your time and expense for a given nouns and adjust you square foot cost as you need. Remember subtract you cost from total charged and what remains is you hourly rate, profit and overhead. Overhead is in the region of 10% and profit should be around 15%.
How can Drano be bleak on pipes when...
Look in the phone book for those that do this type of work and ask for estimates.