When I consult hourly, I bill in 6 minute increments for only focused work. Anything 3 minutes or less doesn't cost you any money. If you have me do something

When I consult hourly, I bill in 6 minute increments for only focused work. Anything 3 minutes or less doesn't cost you any money. If you have me do something that is longer than ~30 minutes, I will charge you from the moment I start to prepare your project, catching the spin-up/context switch time. If you interrupted my focus time with another client, nobody gets charged for my break if I need one to refocus. This is how a lot of lawyers do it, and my clients tend to be familiar with that model. I also charge lawyer-level rates, so I think people appreciate only paying for focused work and receiving an itemized bill. This is all for when I bill hourly - I prefer to bill a project rate instead. Many engineers charge much less per hour but charge for an hour every single time they think about your project. That also works.