This will depend on many things, such as the demand for the particular language, and your skills and experience. For some languages, there may not be much work.  If you are able to find full-time work, the Open Universities Career Guide indicates a salary range for translators and interpreters of between $36,000 and $75,000, with an average salary of $55,000.  If you run your own business, you will need to decide how much you wish to charge. You can get an idea of appropriate rates by doing a web search – some agencies publish their rates online.