Revealing in a post on the Windows blog, Microsoft stated that thanks to a new compression algorithm Windows 10 will be able to save an extra 1.5GB of storage on 32-bit machines, and 2.6GB on 64-bit machines, meaning that if you are planning on using a smaller SSD just to boot up Windows, you will still have a fair amount of storage left for other pieces of software.
This is compared to Windows 8 where Microsoft recommended 16GB for 32-bit machines and 20GB for 64-bit machines. Granted 1.5GB and 2.6GB aren’t particularly huge savings, they’re savings nonetheless and should be welcomed by most users. It also seems that Microsoft’s new compression algorithm will extend to smartphones as well, so handsets running on Windows 10 should be able to free up some extra storage space.
Microsoft also revealed that they have improved upon the Windows recovery tool and it will be able to save as much as 12GB depending on the manufacturer.