You’ve no doubt heard the terms gigabytes, terabytes, or petabytes thrown around before, but what exactly do they mean in terms of real-world storage? Let’s take a closer look at storage sizes.

Words like byte, megabyte, gigabyte, and petabyte all refer to amounts of digital storage. And they sometimes get confused with terms like megabit and gigabit. It’s useful to know exactly what these terms mean (and how they relate to one another) when comparing storage sizes on hard drives, tablets, and flash storage devices. It’s also useful when comparing data transfer rates if you’re shopping for internet service or networking gear.

Bits, Bytes, and Kilobytes

First, let’s take a look at the basics of digital storage with some of the lower level capacities.

The smallest unit of storage is called a bit (b). It’s only capable of storing a single binary digit—either a 1 or 0. When we refer to a bit, especially as part of a larger word, we often use a lower-case “b” in its place. For example, a kilobit is one thousand bits, and a megabit is one thousand kilobits. When we shorten something like 45 megabits, we’d use 45 Mb.

One step up from a bit is a byte (B). A byte is eight bits, and is about what you need to store a single character of text. We use a capital “B” as a shortened form of byte. For example, it takes around 10 B to store an average word.

The next step up from a byte is a kilobyte (KB), which is equivalent to 1,024 bytes of data (or 8,192 bits). We shorten kilobytes to KB, so, for example, it takes around 10 KB to store a single page of plain text.

And with those smaller measurements out of the way, we can now take a look at the terms you’re more likely to hear when shopping for your gadgets.

Megabytes (MB)

There are 1,024 KB in one megabyte (MB). Through around the late 90’s, regular consumer products like hard drives were measured in MBs. Here are few examples of how much you can store in the MB range:

• 1 MB = A 400 page book
• 5 MB = A average 4 minute mp3 song
• 650 MB = 1 CD-ROM with 70 minutes of audio

You’ll see the number 1,024 a lot in the next few sections. Typically, after the kilobyte stage, each successive storage measurement is 1,024 of whatever the next lower measurement is. 1,024 bytes is one kilobyte; 1,024 kilobytes is one megabyte; and so on.

Gigabytes (GB)

So, it should come as no surprise that there are 1,024 MB in one gigabyte (GB). GBs are still very common when referring to consumer levels of storage. Though most regular hard drives are measured in the terabytes these days, things like USB drives and many solid state drives are still measured in the gigabytes.

A few real-world examples:

• 1 GB = around 10 yards of books on a shelf
• 4.7 GB = Capacity of one DVD-ROM disc
• 7 GB = How much data you’re using per hour when streaming Netflix Ultra HD video

Terabytes (TB)

There are 1,024 GB in one terabyte (TB). Right now, TB are the most common unit of measurement when talking about regular hard drive sizes.

Some real-world examples:

• 1 TB = 200,000 5-minute songs; 310,000 pictures; or 500 hours worth of movies
• 10 TB = Amount of data produced by the Hubble Space Telescope per year
• 24 TB = Amount of video data uploaded to YouTube per day in 2016

Petabytes (PB)

There are 1,024 TB (or around one million GB) in one petabyte (PB). If trends continue, petabytes are likely to replace terabytes as the standard measurement for consumer-level storage sometime in the future.

Real-world examples:

• 1 PB = 500 billion pages of standard typed text (or 745 million floppy disks)
• 1.5 PB = 10 billion photos on Facebook
• 20 PB = The amount of data processed by Google daily in 2008

Exabytes (EB)

There are 1,024 PB in one exabytes (EB). Tech giants like Amazon, Google, and Facebook (who process unthinkable amounts of data) are typically the only ones worried about this kind of storage space right now. At the consumer level, some (but not all) file systems used by operating systems today have their theoretical limit somewhere in the exabytes

Real-world examples:

• 1 EB = 11 million 4K videos
• 5 EB = All the words ever spoken by humankind
• 15 EB = Total estimated data held by Google

This list could go on, of course. The next three capacities on the list (for those of you that are curious) are zettabyte, yottabyte, and brontobyte. But honestly, past exabytes, you start getting into astronomical storage capacities that just don’t have much real-world applicability right now.

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