Back in September it was unofficially revealed that Halo 5's install size would be over 45GB, not the biggest download size to hit the Xbox One – but a hefty size none the less. A leaked image of the Halo 5: Guardians box art has not only confirmed this download size, but has added to it.
According to the game's box up to 60GB of storage space is required, with a possibility of additional storage required for "setup, some updates and features, including retention of some gameplay setting and information."
The Xbox One launched with 500GB of room, so, if you have Halo: The Master Chief Collection installed, along with Grand Theft Auto V, Call of Duty: Advanced Warfare, and Battlefield Hardline – you'll already have used up over 200GB of room on your console. That's not even accounting for any other games you've installed and future games you may install (like Black Ops 3, which is 48GB). Consider yourself warned, make room on your Xbox One and prepare yourself for the October 27th release.