Data Storage Converter (KB, MB, GB, TB)
By Santaji GadepatilinUpdated October 27, 2026
Data storage is measured in kilobytes, megabytes, gigabytes and terabytes — in both decimal (1,000) and binary (1,024) units.
How to use the data storage converter
Type a value in any field — decimal (KB, MB, GB, TB) or binary (KiB, MiB, GiB). Every field updates.
Why your drive shows less space
A drive sold as 1 TB holds 1,000,000,000,000 bytes. Windows reports sizes in binary units but labels them “GB/TB”, so it shows about 931 GB. Nothing is missing — it is a units difference.
| Advertised | Bytes | Shown by Windows |
|---|---|---|
| 128 GB | 128,000,000,000 | 119 GB |
| 256 GB | 256,000,000,000 | 238 GB |
| 512 GB | 512,000,000,000 | 477 GB |
| 1 TB | 1,000,000,000,000 | 931 GB |
| 2 TB | 2,000,000,000,000 | 1,863 GB |
| 4 TB | 4,000,000,000,000 | 3,725 GB |
macOS and many Linux tools use decimal units, so they match the advertised size.
Bits vs bytes
Internet speeds are in bits per second (Mbps); file sizes are in bytes. 1 byte = 8 bits, so a 100 Mbps connection downloads at most 12.5 MB/s. See the download time calculator.
How much fits?
| Content | Approximate size |
|---|---|
| Photo (12 MP JPEG) | 3–5 MB |
| Song (MP3, 4 min) | 4–8 MB |
| HD movie (2 h, streaming quality) | 3–6 GB |
| 4K movie (2 h) | 15–25 GB |
| Smartphone OS update | 1–6 GB |
Decimal vs binary
| Unit | Bytes |
|---|---|
| 1 KB | 1,000 |
| 1 KiB | 1,024 |
| 1 MB | 1,000,000 |
| 1 MiB | 1,048,576 |
| 1 GB | 1,000,000,000 |
| 1 GiB | 1,073,741,824 |
A “1 TB” drive holds 1,000,000,000,000 bytes, shown as 931 GiB by systems that use binary units.
Frequently asked questions
What is the difference between GB and GiB?
A GB (gigabyte) is 1,000,000,000 bytes; a GiB (gibibyte) is 1,073,741,824 bytes (2³⁰).
Why does my 1 TB drive show 931 GB?
Drive makers use decimal TB, while some operating systems display binary units. 1 TB = 931 GiB.
How many MB are in a GB?
1,000 MB in decimal units, or 1,024 MiB in a GiB.
How many GB is 1 TB?
1,000 GB in decimal units, or 1,024 GiB in binary units.
Why does my 1 TB drive show 931 GB?
The drive uses decimal units (10¹² bytes), while Windows shows binary gibibytes labelled as GB.