That depends on a number of things:
- How long you record for
- The size of the area that you are recording - the larger the area, the larger the saved file will be
- What recording frame rate you selected - as frame rate is increased, so will the size of the file
- What sort of content you are recording (for example, is it a video game or a static desktop) - a recording with lots of changes will be larger than a recording where very little changes on the screen.
- If sound or a webcam recorded as well - these will both add to the file size compared to if they are not included.
Depending on the answers to each of these, the size of your file could vary considerably.