Will iOS update free up space if it's smaller than the previous iOS update?

hapsap wrote:

I see, so in the settings on the phone itself, it says around 800mb for the update - I presume that's how much space I will loose eventually then? Initial download size will be readjusted and I'll be left with 800mb less - right?

No, that’s the space needed for the installer. After iOS is updated the installer is deleted. So updating will make very little difference in your available space, as SravanKrA explained.

You said:

1. "after the update, the phone will have 0.1GB left to use " --> No
2. "it will install this, but then remove the 4GB": Reference to an iOS 8 may not have much relevance here.

The incremental increase with each update is very minimal because it only replaces a part of the software.

For example between iOS13.5 and iOS13.5.1 the size difference is 44.3 MB See the pic below.

Download Size 44.3MB

After Installation at times it is even lower.

Even while it expands during installation but ultimately the size increase hardly matters

Another example

• between iOS13.4.1 and iOS13.5 the size difference is 355.7 MB See the pic 1 below.
• between iOS12.4.4 and iOS12.4.5 the size difference is 35.9 MB See the pic 2 below.

• Download Size for iOS 13.5 is 355.7 MB
• Download Size for iOS 12.4.5 is 35.9 MB

After Installation at times it is even lower.

Even while it expands during installation but ultimately the size increase hardly matters because it only replaces a part of the software.