Convert GB to MB

One gigabyte equals 1,000 megabytes. To convert any number of gigabytes to megabytes, multiply by 1,000.

The converter above works in both directions and updates as you type. Below you will find the formula, a worked example and a reference table of common values.

Data conversions carry two ambiguities at once. Bits and bytes differ by a factor of eight, and network speeds are quoted in bits while file sizes are quoted in bytes — so a connection and a download will always report numbers that look inconsistent. On top of that, the same prefix means 1,000 to a drive manufacturer and 1,024 to an operating system, which is why advertised capacity and reported capacity never match. Neither is an error; they are different conventions wearing the same name.

GB to MB formula

To go the other way, use gigabyte = megabyte ÷ 1,000.

About these units

Operating systems treat a gigabyte as 2³⁰ bytes while drive manufacturers use 10⁹. This is why a 1 TB drive reports as roughly 931 GB.

A megabyte is 10⁶ bytes decimal or 2²⁰ binary. The gap is about 5%, which is why file sizes and download counters rarely agree exactly.

Gigabyte is also written gigabytes, gbs, gigs and gig. Megabyte is also written megabytes, mbs, megs and meg.

Sources

1. IEC 80000-13:2008, Quantities and units — Part 13: Information science and technology — the decimal byte prefixes and the binary kibibyte series.