MB to GB converter

Type a size with its unit, like `500 MB`, `1.5 GB` or `4 TiB`, and it appears in every unit at once, each with its own copy button. A number on its own is read as megabytes; the setting underneath changes that, and Show first moves the unit you want to the top.

It reads units the way they're written: `MB`, `megabytes`, `MiB`, `Mb` for megabits, `bits` and `bytes`. Lowercase `mb` is read as megabytes, since that's what people mean when they type a file size, and the working says so.

A gigabyte is 1,000,000,000 bytes. That's the SI meaning of giga, and it's what drive makers print on the box. But computers count in powers of two, and for decades software used the same names for 1,024s, with a "kilobyte" of 1,024 bytes and a "megabyte" of 1,048,576.

In January 1999 the International Electrotechnical Commission gave the binary units their own names in IEC 60027-2 Amendment 2, the kibibyte (KiB), mebibyte (MiB) and gibibyte (GiB). The names fixed the ambiguity on paper. Windows still shows binary sizes with the old labels, so a file Windows calls 1 GB is 1 GiB, 1,073,741,824 bytes.

So MB to GB is ÷ 1,000, and MiB to GiB is ÷ 1,024. Mixing them is where the missing space goes. A 1 TB drive holds 1,000,000,000,000 bytes, which Windows reports as about 931 GB, really 931 GiB. Nothing is missing; it's the same bytes counted in a bigger unit.

A byte is 8 bits. Sizes are given in bytes, with a capital B, and network speeds in bits, with a lowercase b: Mb is a megabit, an eighth of a megabyte. To turn a line speed into bytes a second, the Mbps to MB/s converter does it for every unit, and the download time calculator puts sizes and speeds together.

Buyers of hard drives sued over the gap between the two gigabytes. In Cho v. Seagate Technology, a class action begun in 2001 over drives sold as 1,000,000,000-byte gigabytes, Seagate settled without admitting wrongdoing and offered buyers a 5% refund or free backup software. A Western Digital case ended much the same way. Drive makers still use decimal units, and they're correct to: it's what the prefixes mean.