Data Storage Converter
Convert bits, bytes, KB, MB, GB, TB and their binary equivalents (KiB, MiB, GiB, TiB).
Decimal vs binary units
There are two systems for measuring digital storage, which is why a "1 TB" drive shows up as about 931 GB on your computer.
- Decimal (SI) units use powers of 1,000: 1 KB = 1,000 bytes, 1 MB = 1,000,000 bytes, 1 GB = 10⁹ bytes. Drive makers and network speeds use these.
- Binary (IEC) units use powers of 1,024: 1 KiB = 1,024 bytes, 1 MiB = 1,048,576 bytes, 1 GiB = 2³⁰ bytes. Windows and many programs use these but label them "KB, MB, GB".
A 1 TB drive holds 10¹² bytes. Divided by 2³⁰ that is 931.3 GiB, which Windows displays as "931 GB". Nothing is missing; it is a labelling difference.
Bits and bytes
A byte is 8 bits. Internet speeds are quoted in bits per second (Mbps), while file sizes are in bytes. To estimate download time, divide your speed by 8: a 100 Mbps connection moves about 12.5 megabytes per second, so a 5 GB file takes roughly 7 minutes.
How big is each unit?
| Size | Roughly holds |
|---|---|
| 1 MB | A minute of MP3 audio, or a high-quality photo |
| 1 GB | About an hour of standard-definition video |
| 1 TB | About 250,000 phone photos |
| 1 PB | 1,000 TB, data-centre scale |
Frequently asked questions
Why does my 1 TB drive show 931 GB?
The drive is sold in decimal terabytes (10¹² bytes), but the operating system counts in binary gibibytes (2³⁰ bytes). 10¹² ÷ 2³⁰ ≈ 931.
How many MB are in a GB?
1,000 MB in decimal units, or 1,024 MiB in a GiB in binary units.
What is the difference between Mbps and MB/s?
Mbps is megabits per second; MB/s is megabytes per second. Divide Mbps by 8 to get MB/s.
Last reviewed Oct 20, 2026. Results are estimates; check important decisions with a qualified professional.