Data Size Converter bytes
Convert between bytes, KB, MB, GB, and TB, and compare the 1024-based and 1000-based conventions.
What this tool does
Two conventions for data size coexist. One uses 1024 as the multiplier, the other uses 1000. Operating systems and programming languages generally use 1024 while still writing KB, MB, and GB, whereas storage manufacturers and network speed ratings use 1000.
That difference is why a 1TB drive shows up as roughly 931GB once connected. Nothing is missing: the manufacturer counted 1TB as 1,000,000,000,000 bytes and the operating system divided by 1024. The IEC notation KiB, MiB, and GiB exists to label the 1024-based units unambiguously, but in practice KB and MB are still used for both.
This tool converts an input value into several units at once so the number you need for a setting or a limit is immediately available.
When to use it
Use it when expressing an upload limit in bytes, when calculating memory values for a server configuration, when converting log or database sizes into another unit, or when preparing transfer volume figures for an estimate.
Input and output examples
1024 KB
1 MB / 1,048,576 bytes
Converted with the 1024-based convention.
1 TB
1024 GB binary, versus a 1000-based 1TB device shown as about 931 GiB
The reason drive labels and operating system reports disagree.
Notes and limitations
Check which convention the target software uses. The nginx client_max_body_size directive and the PHP upload_max_filesize setting interpret suffixes as 1024-based, while cloud billing is often 1000-based. Remember too that bits and bytes differ by a factor of eight, so network speeds in Mbps should not be compared directly with file sizes in MB.
Frequently asked questions
Why does a 1TB disk show as 931GB?
The manufacturer counts 1TB as one trillion bytes while the operating system divides by 1024. No capacity is lost; the notation differs.
How do KB and KiB differ?
KiB is the IEC notation for exactly 1024 bytes, whereas KB strictly means 1000 bytes, although KB is often used loosely for 1024.