What are You Worth (per hour)??
I've re-vamped my handy hourly-rates calculator so that it looks better on your phone. I wrote it years ago to get a better idea of what to charge for freelance work. It's surprising (even now) how high the hourly rate must be to generate a living wage. It's also fun to see how much you're costing your employer if you have a regular job. When you choose billable hours, remember that freelancers often can only charge a few hours a day because they also spend time on advertising, accounting, cleaning, invoicing, training, and other background tasks.
I've got lots of other calculators, but this one should appeal to almost everyone.