File Size Converter
Convert a file size to every unit at once — decimal (KB, MB, GB) and binary (KiB, MiB, GiB).
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How to convert file sizes
- Type a number and choose its unit, such as 500 MB.
- Read it in every other unit, in both decimal (KB, MB, GB) and binary (KiB, MiB, GiB).
About this tool
"Decimal" units (KB, MB, GB, TB) step by 1,000 and are what storage manufacturers advertise and what the SI system defines — a 1 TB drive is 1,000,000,000,000 bytes. "Binary" units (KiB, MiB, GiB, TiB) step by 1,024 and are what operating systems typically show you (macOS switched to decimal reporting some years back; Windows still generally uses binary maths but labels it with decimal unit names, which is the single biggest source of "my drive shows less space than advertised" confusion). This tool keeps the two systems clearly separate so you can see both at once.
Nothing you enter here is sent to a server — the entire tool runs as JavaScript in your browser tab.
Questions about file sizes
How many MB are in a GB?
1,000 in decimal units, which drive makers use, or 1,024 MiB in a GiB in binary units, which Windows uses.
Why does my 1 TB drive show about 931 GB?
The drive has 1,000,000,000,000 bytes. Windows divides by 1,024 three times, giving 931 GiB, but labels it GB.
What is the difference between KB and KiB?
A KB (kilobyte) is 1,000 bytes; a KiB (kibibyte) is 1,024 bytes. The same pattern continues for MB/MiB, GB/GiB and TB/TiB.
How many bytes are in a megabyte?
1,000,000 bytes in a decimal megabyte (MB), or 1,048,576 bytes in a binary mebibyte (MiB).