File Size Converter

The File Size Converter is a free online file size converter that translates between bits, bytes and every common storage unit — kilobytes, megabytes, gigabytes, terabytes, petabytes and their binary counterparts KiB, MiB, GiB, TiB and PiB. It's built for anyone comparing a download size to available storage, checking whether a video file will fit on a USB drive, or trying to understand why a purchased '1 TB' drive shows less space than expected in the operating system.

It answers everyday questions like a straightforward mb to gb or kb to mb conversion for a file listing, as well as the trickier gib vs gb question that trips up a lot of people: drive manufacturers advertise storage in decimal units (1 GB = 1,000³ bytes = 1,000,000,000 bytes), while operating systems like Windows traditionally report free space in binary units but label them with decimal names (showing 'GB' when it actually means GiB). This converter handles both systems explicitly, so you can translate a marketing size into the real capacity your OS will report, or vice versa.

The binary units follow powers of 1,024 rather than 1,000: 1 KiB = 1,024 bytes, 1 MiB = 1,024² bytes = 1,048,576 bytes, 1 GiB = 1,024³ bytes = 1,073,741,824 bytes, and so on up to PiB. The decimal units follow the standard SI powers of 1,000 (1 KB = 1,000 bytes, 1 MB = 1,000,000 bytes, 1 GB = 1,000,000,000 bytes). Because the gap between the two systems compounds at each step, the difference between a decimal and binary unit grows from about 2.4% at the kilo level to nearly 10% at the terabyte level — exactly why a '1 TB' drive reads as roughly 931 GiB rather than 1,000.

The tool also converts to and from bits, which is essential for relating a download or internet speed quoted in megabits per second to a file size quoted in megabytes — remember there are 8 bits in a byte, so an advertised '100 Mbps' connection tops out at 12.5 MB/s in practice. Every conversion is computed precisely in your browser with no upload or server round-trip involved.