Pricing your work is always difficult. This is especially true in any industry that deals with intangibles like software, literature or other works of art. It is common for inexperienced teams to start by invoicing by the hour. In traditional tangible work - like digging a well - hours are usually interchangeable: A stronger or more motivated worker can dig slightly faster but variations are generally small and predictable. In any work dealing mostly or only with brain power, differences in productivity for different individuals or even days can be huge.