When to use it
Use this converter to switch between bits, bytes, kilobytes, megabytes, gigabytes, terabytes and petabytes, and their binary versions: kibibytes, mebibytes, gibibytes, tebibytes and pebibytes. It explains why a new drive looks smaller than advertised and helps you estimate download times, cloud storage needs and file size limits.
How to use it
- Enter the size in Value.
- Choose the unit you have, such as Gigabytes (GB).
- Choose the unit you want, such as Gibibytes (GiB).
- Read the result, or click Copy result.
- Use the swap button to reverse the conversion.
The All conversions table shows the same amount of data in all twelve units.
Worked example
You buy a 500 GB SSD, and Windows says it is 465 GB. Enter 500 with gigabytes and gibibytes selected. The result is 465.6612873 GiB. Windows is showing gibibytes with the label GB, so the full 500 GB is there.
The bigger the drive, the bigger the gap. A 1 TB drive is about 0.909 TiB, which Windows shows as roughly 931 GB.
Decimal and binary units side by side
| Decimal | Bytes | Binary | 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 |
At the kilobyte level the difference is only 2.4%, but by the terabyte level it grows to about 10%.
Estimating download time
Internet speed is measured in bits, so convert it first. A 100 Mbps connection moves about 12.5 megabytes each second at best. A 4 GB game would take about 5 minutes and 20 seconds under perfect conditions, and usually longer in practice.
File size limits
Email attachments are often limited to around 20 to 25 MB. If a service gives its limit in MiB, convert your file size first, so you know whether it fits before you try to send it.
Tips
- Check which units an app uses. Phones, cloud storage and operating systems do not all agree.
- Use bits for network speeds. Mbps and Gbps measure speed, not storage.
- Leave room on drives. Computers slow down when storage is almost full, so plan for about 10 to 20% free space.
Common mistakes
- Mixing up Mb and MB. A small b means bits and a capital B means bytes, a factor of eight.
- Thinking a drive is faulty. The difference between advertised and shown size is normal.
- Adding binary and decimal sizes together. Convert everything to one system first.