How many megabytes are in a gigabyte?
Officially, there are 1000 (103) megabytes (MB) in a gigabyte (GB). So 500MB would equal 0.5 GB.
This definition is used in hard drives, portable memory drives (memory cards, USB drives), DVDs, Blu-ray disks, and most measures of
performance. Some software (such as Mac OS X and the Linux kernel) uses this definition when displaying file and disk sizes.
MB stands for megabyte. Mb with lowercase b is ambiguous, as it has been used for both “megabyte” and “megabit”. Writing megabytes as MB
and megabits as Mbit avoids any confusion.
Memory manufacturer definition
Another definition is used by memory manufacturers and some software, like Microsoft Windows. They use 1024 (210) megabytes per gigabyte,
but this is more properly called a gigabinary byte (GiB), sometimes contracted to gibibyte.
Using the non-standard definition:
1 megabyte (MB) = 1024 kilobytes (KB) 1 gigabyte (GB) = 1024 megabytes (MB) or 8192 megabits (Mb)
1,000 megabyte (MB) = 1 gigabyte (GB) 1,024 mebibyte (MiB) = 1 gibibyte (GiB) 1 megabyte = 8 megabits mega- = 1,000,000 giga- = 1,000,000,000 mebi- = 1,024 × 1,024 = 1,048,576 gibi- = 1,024 × 1,024 × 1,024 = 1,073,741,824