Not Possible , as each job has a different rate, Plumbing / Gas different also depends on time of day, and remember they deduct 20% tax, you will get a % mark up on materials, I always use there account for drawing fittings / Boiler parts, some jobs can be done in 15 min you still get the full Hr , use t get 50% work got a bit tight and its down to 40% at the moment , average job 1hr worth to you £33 after tax, depending where you live you could quite easy get in 10 a day, its what you make of it, use it to fill in gaps , but don't rely on it for your main income , For what I do now it fits in very well , don't bother much now with install work, quite happy pottering about on small jobs, get by on what I earn, finish when I want & no stress or winging customers.