Despite the fact that they’re similar words with similar abbreviations, megabits (Mb) and megabytes (MB) are different units of measurement. Here’s what they measure, and when they’re used.

## Bits vs. Bytes

If you’ve shopped for a plan from an internet service provider (ISP) recently, you might have noticed that the company promoted its broadband speeds in terms of mega- or gigabits per second. On the other hand, most mobile or internet plans with data caps measure your maximum usage in terms of mega- or gigabytes.

You might think these two figures are the same. However, a “bit” and a “byte” are distinct units of measurement that are used for different things. Each byte is comprised of eight bits. Therefore, one megabyte is equal to eight megabits, eight megabytes are equal to 64 megabits, and so on.

Furthermore, they are abbreviated differently. A bit is abbreviated using a lowercase “b” (Mb or Mbit), while a byte is abbreviated with an uppercase “B” (MB). When denoting these in terms of speed, megabits per second is abbreviated as “Mbps,” while megabytes per second is abbreviated as “MB/s.”

## Converting Bits to Bytes

To illustrate the difference better, let’s use a real-world scenario. Say you’ve recently subscribed to a fiber broadband connection that promises maximum internet speeds of 400 Mbps. You’re about to download a video file that’s 800 megabytes. Assuming your internet is working perfectly and its servers are fast, how long would it take to complete this download?

## Measuring with the Bit

Bits are primarily used by ISPs to measure bandwidth. These numbers are referred to as “bit rates.”

Many people wonder why the download time for a file rarely matches the promised bitrate of their connections. This is due to the difference between bandwidth and speed. Your network’s bandwidth refers to the maximum amount of data it can transfer within a certain period of time, like 1 second.

On the other hand, your network’s speed is the actual transfer rate of data from an online server to your device, or vice versa. This can vary significantly between providers, connection types, and locations.

Therefore, two households might both have gigabit connections, but because they’re located in different cities, their down- and upload speeds might vary. While their “potential” internet speeds might be the same, they’re likely very different in reality.

## Using the Byte

Bytes are used for pretty much everything related to file size and storage. All forms of storage—from solid-state drives, to cloud services, like Dropbox—are referred to in terms of byte capacity. The files on your computer are also measured in bytes.

The reason we use bytes instead of bits to measure files goes back to the earliest days of computing. Each bit can have a value of either zero or one. When combined, they make a byte, which was the minimum amount of memory a computer could read and process. Each byte would then correspond to a text character.

Since then, files have become more complex, and the individual byte has become an incredibly small unit of measurement. Most of the files on your computer are at least a kilobyte, or 1,024 bytes.

## Mega, Giga, Tera, and More

When measuring data in terms of bits or bytes, it’s essential to know the following commonly used unit prefixes:

• 1,024 kilobytes = 1 megabyte
• 1,024 megabytes = 1 gigabyte
• 1,024 gigabytes = 1 terabyte

(This is actually the traditional binary form—according to the International System of Units, one megabyte is in fact 1000 kilobytes, a gigabyte is in fact 1000 megabytes, and so on. Different devices and software programs don’t always share the same definition.)

Most hardware is measured up to terabytes, while most connection speeds are measured up to gigabits.

It’s also handy to know some quick conversions for the numbers used for internet plans. Below are some useful figures for measuring your potential maximum download speed:

• 25 megabits per second = 3.125 megabytes per second
• 100 megabits per second = 12.5 megabytes per second
• 1 gigabit per second = 125 megabytes per second

Remember to always be wary about the bandwidth promised by ISPs. When in doubt, search online to find out what the average internet speeds are in your area.

Vann Vicente
Vann Vicente has been a technology writer for four years, with a focus on explainers geared towards average consumers. He also works as a digital marketer for a regional e-commerce website. He's invested in internet culture, social media, and how people interact with the web.