Difference Between Megabits and Megabytes

Understand the difference between Mbps and MB, why internet speeds use one and files use the other.

2 min read

Quick Answer

Megabits (Mb) and megabytes (MB) are both data measurements, but 1 megabyte equals 8 megabits. Internet speeds are measured in megabits per second (Mbps), while file sizes use megabytes (MB). A 100 Mbps connection downloads at about 12.5 MB per second, not 100 MB.

Key Takeaways

A bit is the smallest unit of digital data (a single 0 or 1).
Storage devices use bytes (GB, TB), while network equipment uses bits (Gbps).
The abbreviations matter: Mb = megabits, MB = megabytes (note capitalization).

Explanation

A bit is the smallest unit of digital data (a single 0 or 1). A byte is 8 bits. The prefixes mega, giga, and tera mean million, billion, and trillion respectively. So 1 megabyte (MB) = 8 megabits (Mb), and 1 gigabyte (GB) = 8 gigabits (Gb).

Internet service providers advertise speeds in megabits per second (Mbps) because the larger numbers look more impressive. A 100 Mbps plan sounds faster than saying 12.5 megabytes per second, even though they are the same. This is not deceptive, just industry convention.

To calculate download times, divide your speed in Mbps by 8 to get MB per second. A 1 GB (1,000 MB) file on a 100 Mbps connection takes approximately 80 seconds: 1,000 MB ÷ 12.5 MB/s = 80 seconds. Real speeds are often lower due to overhead and network conditions.

Things to Know

Storage devices use bytes (GB, TB), while network equipment uses bits (Gbps).
The abbreviations matter: Mb = megabits, MB = megabytes (note capitalization).
1 GB technically equals 1,024 MB in computing, but storage manufacturers often use 1,000 MB.