The size of the saved file while depend on a number of factors so it is difficult to accurately predict how large it will be until your actually save it.
The key factors are:
- 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
- Which record mode you have selected – MPEG record mode will generally produce smaller than GDI record mode, particularly when recording moving video
- What sort of content you are recording. For example, is it a YouTube video or a static desktop? A recording with lots of changes will be much larger than a recording where very little changes on the screen.
- What recording frame rate you selected – as frame rate is increased, so will the size of the file
- If sound or a webcam recorded as well – these will both add to the file size compared to if they are not included.