Terabytes to Gigabytes Converter

Digital data is counted in bits — a single 0 or 1 — and grouped into bytes, where one byte is eight bits. The tricky part is that the prefixes kilo, mega and giga have two meanings. Under the decimal (SI) system a kilobyte is 1,000 bytes, a megabyte is a million bytes and a gigabyte is a billion bytes; this is what storage makers use, so a “1 TB” drive holds exactly 10¹² bytes. Under the binary (IEC) system the matching units are the kibibyte (1,024 bytes), mebibyte and gibibyte (KiB, MiB, GiB), which grow in powers of 1,024. The two only line up at the byte: 1 GB is about 0.931 GiB, which is why a 1 TB drive shows up as roughly 931 GB in Windows — the operating system is really counting gibibytes but labelling them “GB.” A second common mix-up is bits versus bytes: network and download speeds are quoted in bits per second (Mbps), while file sizes are in bytes, so a 100 Mbps connection downloads at about 12.5 MB per second. This converter keeps decimal and binary, and bits and bytes, in clearly separated groups so you always know exactly which unit you are working with.