[username3]

My 64GB iPad has 57.1GB free space. That's 89%.

57.1 - 32 - 16 = 9.1; 9.1 / 16 = 0.56875; 16GB iPad has 9.1GB free space? That's 56%.

My 16GB iPhone 5 has 13.4GB free. That's 83%.

13.4 + 16 + 32 = 61.4; 61.4 / 64 = 0.959375; 64GB iPhone 5 has 61.4GB free space? That's 95%.

Edit: These calculations are not accurate. Read replies.

[danpalmer]

This would seem to be correct but doesn't take into account different hardware specs.

For a start, the larger the disk, the more is used for formatting and is lost due to the difference in how manufacturers specify sizes, so you can't just add/subtract storage amounts, you need to scale.

Also, different combinations of processor, cellular modem, etc, will require different parts of the operating system, and Apple differentiates between these in the distributions it provides. It's not a massive difference, but it is something.

Finally, on Mac OS, the operating system reserves some space for a memory dump if the device loses power so that it can resume where it left off. This means if you have 8GB of RAM, you will always have 8GB of disk space reserved (search for sleepimage). I don't know for sure, but iOS may do something similar.

[username3]

I agree with this. Also, if they calculate space in GiB instead of GB, we should add/subtract 14.9 and 29.8.

[twoodfin]

Some quick web searching suggests that the 16GB iPad has closer to 13.5GB free.

My guess is that iOS reserves more space on the larger devices for its own internal use.

[nwh]

The amount also varies by the version of iOS installed, and if delta updates have been applied (they take up a lot more room, though I'm not sure why).

[revscat]

I have a 16GB iPad sitting here in front of me. The Usage preference pane on the device currently shows "11.1GB used, 2.3GB available."

That's 13.3GB, or 83%.

[nextparadigms]

Yeah, when I see these comparisons about "percentage" of free space, I find them pretty ridiculous, because they compare the iPhone or the iPad at 16 GB, and say it's like 80%, and then the Surface at 64 GB.

If you're going to compare it like that then compare it with the 64 GB iPad, and then you get the free space to be almost 3x larger than on the 64 GB Surface (95% vs ~35%).

[simias]

I'm a bit tired but your calculations make no sense to me. What are you getting at?

[TheAnimus]

My 8GB nexus couldn't update the other day. I had to move off the 3GB of videos I had on it.

I don't know how much is the shipped apps. But i'd hazard a guess it is really close to 50%.

[rmrfrmrf]

what?