How to convert data sizes
- Enter the value.
- Choose the From and To units. Decimal units (KB, MB, GB, TB, PB) and binary units (KiB, MiB, GiB, TiB) sit in the same list.
- Read the result, the factor both ways and a table with the size in every unit.
Decimal and binary, side by side
There are two systems, and mixing them is the cause of most confusion.
| Decimal (SI) | Bytes | Binary (IEC) | 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 |
| 1 TB | 10¹² | 1 TiB | 1,099,511,627,776 |
The gap grows with size: about 2.4% at KB, 4.9% at MB, 7.4% at GB and 10% at TB. Windows labels binary sizes as GB, while macOS and most storage makers use decimal.
Worked example
You buy a 512 GB phone. How much will a system that counts in binary units show?
- 512 GB = 512 × 10⁹ bytes = 512,000,000,000 bytes.
- In GiB: 512,000,000,000 ÷ 1,073,741,824 = 476.8 GiB.
- The difference of 35 GB is not lost. It is the same bytes counted another way, before the system files take their share.
For a download, a 700 MB video is 0.7 GB or 667.6 MiB.
Bits and bytes
A byte is 8 bits. Internet providers sell speed in megabits per second (Mbit/s), while files are shown in megabytes. Divide the line speed by 8 to estimate download speed in megabytes.
Popular pairs
The most searched conversions are MB to GB and GB to TB, each with a table of common values. For other measures, see the speed converter or the length converter.
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