How are rates calculated?
For translation, we usually calculate the rate by the number of source words (the number of words in the text to be translated). They depend on the language pair, the level of technicity of the text, of its length, and the deadline for the delivery. However, in case it is impossible to automatically determine the number of words in a document (in hard copy documents for example), we can either estimate manually the number of words or charge by the number of words in the target text (translated text).
For proofreading/revision, I charge by the hour. Again, it depends on the technicity of the text and the deadline.
For interpreting, I charge by day or half-day depending on the missions.