A new 1TB SSD showing about 931GB does not automatically mean storage has disappeared. First check how the number is calculated. Other discrepancies still deserve investigation: the conversion table and checking sequence below help separate a unit difference from a device or partition question.
- Read the label’s unit
- Separate total and free space
- Convert the same byte count
- Check partitions and model for the remaining difference
One byte count, two ways to measure it
A manufacturer’s 1TB normally represents 1,000,000,000,000 bytes. One binary GiB represents 1,073,741,824 bytes. Dividing the same byte count by the larger unit gives a smaller number. Some Windows displays label this binary calculation as GB, making the comparison confusing.
The calculation is 1,000,000,000,000 ÷ 1,073,741,824 = about 931.32GiB. This is a conversion before allowing for a file system or separate partitions. If a specification actually says 1TiB, it describes a different byte count; read the unit on the label rather than assuming every “tera” means the same thing.
Use the table for total capacity, not free space
These examples convert decimal manufacturer capacities into binary GiB. They are neither measurements of a tested drive nor predictions of available space. The whole device, one partition and the free space inside that partition are three different quantities.
A 1TB device may therefore be recognised at about 931GiB while offering much less free space after an operating system, apps and personal files have been stored. Comparing “free space” directly with the box label counts your stored files as if they were missing capacity.
| Label | Decimal bytes | Binary conversion |
|---|---|---|
| 500GB | 500,000,000,000 | about 465.66GiB |
| 1TB | 1,000,000,000,000 | about 931.32GiB |
| 2TB | 2,000,000,000,000 | about 1,862.65GiB |
What to check when the difference is larger
First record the exact model and its specified capacity. Then write down the selected drive’s total capacity and free space separately. Finally, inspect the operating system’s disk-management view for other partitions or unallocated space. This is an observation task; it does not require formatting or deleting a partition.
If the whole device’s byte count differs greatly from its specification, or its model identification does not match, send the label and relevant screen to the seller or manufacturer for clarification. A unit conversion cannot prove authenticity or correct operation. Preserve a separate copy of important files before considering any changes to partitions.
A worked example
Example worksheet: box 1TB / whole device about 931GiB / selected partition about 900GiB / free space 640GiB. The 1,000-to-931 difference is explained by units. The 931-to-900 difference calls for a look at partitions. The 900-to-640 difference calls for a look at stored data and space usage. These are invented worksheet values, not a benchmark or diagnosis of your drive.
Common questions
Does 931GB mean the SSD is faulty?
Converting a decimal 1TB to binary units gives about 931GiB. That number alone does not establish drive health; check the whole device and its exact model.
Will formatting make it 1,000GB?
Formatting cannot increase physical capacity when the discrepancy comes from units. It can erase data, so do not use it to fix a display-number difference.
If only 700GB is free, has the rest vanished?
Free space excludes stored files and other space usage. Compare it with total capacity in the same view first.
Official sources checked
Official source checked on 9 October 2026. Tables and examples are our calculations for explaining units, not first-hand product tests.