Drive Space Calculator
Bought a 2TB SSD and Windows says about 1.8TB? Nothing is missing. Enter the size on the box to see what Windows will show, and how many games will fit.
An example value. Check the storage requirement on each game's store page.
Room for updates, Windows and other files. Set 0 to ignore.
- Windows shows
- Difference
- Games that fit
Why the numbers differ. Drive makers count a gigabyte as 1,000,000,000 bytes. Windows counts a "GB" as 1,073,741,824 bytes (1,024 × 1,024 × 1,024), so the same drive looks about 7% smaller, and the gap grows to about 9% in terabytes. The bytes are all there; they're just counted in bigger units.
If it's much smaller than this. Open Disk Management (right-click Start) and look for unallocated space or extra partitions, which can happen after cloning a smaller drive. For moving games onto a new drive, see how to move Steam games to another drive.
How this works
- Drive makers count in decimal units: 1 GB is 1,000,000,000 bytes and 1 TB is 1,000,000,000,000 bytes. The tool converts the advertised size to bytes.
- Windows counts in binary units, where its "GB" is 1,073,741,824 bytes (2^30, a gibibyte) and its "TB" is 2^40 bytes. Shown size = bytes ÷ 1,073,741,824.
- Games that fit = (space available − space you want to keep free) ÷ average game size, rounded down.
The usable space is a little lower than the result, because the file system and any recovery or system partitions also take room. Game sizes vary widely and grow with updates, so the game count is a rough guide.
Where the figures come from: Decimal SI prefixes and the binary prefixes defined by NIST; Seagate's explanation of why a 1TB drive shows about 931GB.