That depends on the amount of RAM you have in there?
256 MB = 121 MB Free
512 MB = 314 MB Free
1024 MB = 714 MB Free
2048 MB = 1600 MB Free
The above can get fragmented and really be lower that posted. There are cache/memory to free up the RAM and cache memory to give you more free. Free Memory Cleaner FMR can give you the max free. Shown above.
Android OS Donut 1.6 Eclair 2.x, Froyo 2.2, Gingerbread 2.3.x thru Ice Cream 4.0.3, 4.0.4, an 4.0.1 Jelly Bean uses about 2GB part of the IS
IS = internal storage on 4GB = 2GB
IS = internal storage on 8GB = 5GB
IS = internal storage on 16GB = 14GB
IS = internal storage on 32GB = 30GB