I understand that a drive advertised as 2 TB appears as roughly 1.8 TB in Windows because manufacturers and operating systems use different units. What does that mean in practice when downloading games or other large files? If a game or file is listed as 100 GB, could I fit twenty of them on the drive, or is the real limit closer to eighteen?
4 Answers
The answer depends on which unit the file size uses. If each file is truly 100 GB in decimal units, twenty would theoretically fit in 2 TB. If Windows reports each one as 100 GB while actually meaning 100 GiB, then only about eighteen would fit on a 2 TB drive, and even that ignores formatting and filesystem overhead.
You also should not plan to use every last byte of the drive. Filesystems use some space for their own data, and leaving free room is especially helpful for SSDs and updates. A fixed 20% rule is not mandatory, but keeping at least some meaningful amount of free space is a good idea; dropping below roughly 5–10% can cause practical problems.
Steam can make this a little less predictable. Its download size may be smaller than the final installed size because the files are compressed, and the size shown in system requirements may not always match the current installation size. Check the actual free-space requirement before installing.
The drive manufacturer is using decimal units: 2 TB means 2,000,000,000,000 bytes. Windows traditionally displays that capacity using binary units, although it labels them as TB instead of the more accurate TiB. That works out to about 1.82 TiB, which is why the drive appears as roughly 1.8 TB.
The manufacturer is not mislabeling the drive—2 TB really is 2 trillion bytes. The confusion comes from Windows using binary calculations while still displaying the older TB label.