Data sizes and internet speed: MB, MiB and Mbps explained

Bits and bytes

A byte is 8 bits. Internet speeds are given in bits per second (Mbps); file sizes in bytes (MB, GB). To turn a speed in Mbps into megabytes per second, divide by 8.

1000 or 1024?

• GB (gigabyte) = 1,000,000,000 bytes — used by drive makers.
• GiB (gibibyte) = 1,073,741,824 bytes — often what operating systems actually count.

That's why a 1 TB drive shows about 0.909 TiB on a computer: nothing is missing, it's the same space in a different unit.

Estimating a download

seconds = file size in megabits ÷ speed in Mbps

Example: a 2 GB file is 2 × 8,000 = 16,000 megabits. At 20 Mbps: 16,000 ÷ 20 = 800 seconds, about 13.3 minutes. Real downloads are usually a little slower than the line speed.

Convert any unit

ZIBADIS Yottabyte has a data-unit converter that works with both the 1000-based and 1024-based units, from bits to yottabytes.

Tools for this

• Data unit converter
• Network calculator