That depends on the engine that you are using. Once in orbit around the Earth, the answer might be "none", as there are (very weak) engines that run on electricity and emit xenon ions, but with no air in space to slow you down, you don't need a powerful engine.

Getting into orbit on the other hand requires a much more powerful engine, and I don't know the exact amount of fuel you need, although that, too, depends on the size of your spacecraft.