Preload download
12.9 GB
Compressed size pulled by the Steam client during the pre-launch preload window.
Install prep
Subnautica 2 Download Size
The actual number Steam is downloading right now, plus the install gotchas per storefront. Updated against the live Steam preload and Unknown Worlds' pre-purchase announcement.
12.9 GB preload, 14.56 GB after install. Confirmed against the Subnautica 2 Steam preload that went live for 72 hours before launch. The 50 GB figure on the Steam store page is the "available storage" requirement under PC specs, which is the conservative buffer Steam asks for, not the real footprint.
After install
14.56 GB
Disk footprint once Steam finishes unpacking the preload.
Steam page requirement
50 GB
The "available storage" buffer Steam lists under PC requirements. Useful as a patch headroom number, not the real install size.
By storefront
Steam
Preload pulled 12.9 GB. The install dialog in the Steam client shows the live number; if you skipped preload, the launch-day download will be the same volume.
Epic Games Store
Preload was made available alongside Steam. Numbers track close to Steam, but Epic does not always show a separate compressed figure before the install starts.
Xbox (console)
Preload is handled through the Xbox app or console store the same way as any pre-ordered game. Console package sizes can differ slightly from PC due to platform compression.
PC Game Pass
No preload available. The download begins after the game unlocks on May 14, 2026. Plan for the full ~12 to 14 GB to come down at launch time on PC Game Pass.
Will this number change?
Subnautica 2 is in Early Access. Each patch can add biomes, creatures, or assets, so the install size will grow over time. The 50 GB Steam buffer is a sensible amount to keep free if you plan to follow the Early Access roadmap all the way to v1.0.
Right now, a 1 TB drive that is already 80 percent full is going to be fine for launch but tight once shader cache, save backups, and a few large patches stack up over the coming months.
Other install-day questions
Storage is one decision. These cover the rest.