Home » Computer Guides » Computer Tech Guides » What Are Kilobytes, Megabytes, Gigabytes And Terabytes

What Are Kilobytes, Megabytes, Gigabytes And Terabytes

If you’re using a computer in any way at all, you just have to bump into Kilobytes, Megabytes, Gigabytes & Terabytes. But what exactly are they? And how do they relate to each other.? Well, in short, they are simply a way of measuring either, how much data we’ve got, or, how much space we’ve got to store that data.

Imagine you’ve got two litres of water, you’re gonna need a jug or bucket of at least 2-litre capacity, to store that water in. That’s obvious, right?

In exactly the same way, if you’ve got 2 Gigabytes of data, then your gonna need a device with at least 2 Gigabytes of storage capacity to store that data.

What are Bits And Bytes?

Before we can get a grip on what exactly Kilobytes (KB), Megabytes (MB) and Gigabytes (GB) are, we need to know where they come from.

It all starts with the humble Bit. That then leads to Bytes. So what are bits and bytes?

What Are Bits?

Computers store data (any type of file, document, picture etc) as ones and zeros. How Does A Computer Store Data?

These ones and zeros are called Bits. They are tiny bits of data. In fact, a bit is the smallest amount of data you can have.

A series of ones and zeros. A single one is marked with a callout as being a bit.
A single bit of data.

What Are Bytes?

A Byte is 8 bits, or put another way, 8 ones and zeros.

In effect, what we’re doing is counting the number of ones & zeros. The number of Bits.

And really, that’s all Kilobytes (KB), Megabytes (MB) and Gigabytes (GB) are doing. They’re just counting the number of ones and zeros, as you’ll see.

A series of ones and zeros. A single one is marked with a callout as being a bit.
8 ones and zeros (bits) equals 1 Byte.

Why Change At 8?

When we get 8 bits we call it a 1 Byte. Changing at 8 is strange, why not change at 10, it’d be much easier if we said there are 10 bits to a Byte. But that’s only if you’re counting in the decimal system, which is what we humans do.
Computers, on the other hand, count in the binary system, and to them, changing at 8 makes perfect sense. But don’t worry about that. We just need to know that when you’ve got 8 Bits, you can call them collectively 1 Byte.

To See What A Byte Is.

Try doing this for yourself on your own computer.

Open Notepad on your computer, then type a single letter or number. Nothing else, no spaces, full stops, commas or anything, just a single letter or number.

Save the file onto your desktop.

Notepad is open and a single letter "a" has been typed.
Type a single letter or number into Notepad. Here I’ve typed the letter “a”.

Find the file on your Desktop, right-click it, then left-click PROPERTIES on the menu that appears.

You’ll see that the size of the file is 1 Byte.

That’s because every character that you can type into Notepad is represented by 8 bits, or 8 ones & zeros, or 1 Byte.

Properties dialogue box open. Size of file is highlighted.
The file is exactly 1 Byte. Or 8 bits.

Now try opening the file again in Notepad and add more letters and numbers. Add some spaces and grammar. Resave the file and check out the increase in the size of the file.

What Are Kilobytes And Megabytes?

OK, so far we’ve got 8 bits to the byte. And 1 byte is equal to a single letter in Notepad. Just one letter. So a single byte is a tiny amount of data. It doesn’t tell you a lot.

To get anything meaningful, to create a proper document with some meaningful information, we’d need lots and lots of bytes.

Consider for a moment how many Bytes we’d need for a 5000-word essay or report.

Remember that it’s 1 Byte for every single letter, not every word. Every letter, every space and every punctuation mark is 1 Byte, or 8 bits or 8 ones and zeros.

You can see that the number of Bytes will be huge because a Byte is such a tiny amount of data.

This is where Kilobytes and Megabytes come in.

2 paragraphs of text in Notepad.
This is what 1 Kilobyte of text looks like. Not much is it?

The Metric System.

In the metric system, whenever you reach 1000, you add the word Kilo. 1000 metres becomes 1 Kilo-metre, 1000 litres becomes 1 Kilo-litre
So 1000 Bytes could become 1 Kilo-Byte. It would make sense, wouldn’t it?
Now, remember that we’re counting the number of Bits, the number of ones & zeros.
So 1 KB is 1000 Bytes, and 1 Byte is 8 Bits.
So 1 Kilobyte is 8000 Bits, or 8000 ones & zeros.


A single Kilobyte isn’t really that much data. In fact, it’s still tiny. That means that we’ll quickly build up many thousands and thousands of Kilobytes.

Again, the numbers start to become huge and unmanageable. What we need is to change up again. When we reach 1000 Kilobytes, we need to call it something else. But what?

Mega means 1 million and 1 thousand Kilobytes is 1 million Bytes.

So it makes perfect sense to call 1000 Kilobytes a Megabyte. It works.

A Megabyte is starting to become a reasonable amount of data.

As an example, the average 3-minute pop song weighs in at around 40 Megabytes

A colourful CD with musical notes drifting from it.
A 3-minute song on CD is around 40 Megabytes.

How Many Bits In A Megabyte?

Here we go,
1 Megabyte is 1000 Kilobytes. 1 Kilobyte is 1000 Bytes and 1 Byte is 8 bits (or 8 ones & zeros).
So 1 Megabyte is 1000 x 1000 x 8 = 8 million bits or 8 million ones & zeros.
Taking a pop song at around 40 MB, then that works out to be, 320,000,000 bits. That’s a lot of 1s and 0s
You can see why we have to reduce the sheer size of the numbers.

What Are Gigabytes And Terabytes?

There was a time when a Megabyte was considered to be a huge amount of data. After all, it’s 8 million ones & zeros. But not anymore. Today, a Megabyte is a relatively small amount of data. So where do we go next?

We’ve gone from Bits to Bytes (which are both tiny), to Kilobytes (which are very small), to Megabytes (which are small, but significant).

In mathematics, a Giga or Giga symbol means 1 billion.

You can see where this is going.

A Gigabyte is 1000 Megabytes. Which works out to be 1 billion Bytes or 8 billion bits. 8 billion ones & zeros.

A single-layer DVD can hold 4.7 Gigabytes of data.

Which is 37,600,000,000 ones & zeros.

Or 1 DVD movie.

A DVD movie disk.
The movies at home. Pop in a DVD and fetch the popcorn.

Terabytes And Beyond.

Gigabytes were considered to be so huge an amount of data, that no one really thought we’d need to go past them. But that didn’t last long. So what’s next?

After Gigabytes, we change to Terabytes.

1 Terabyte is equal to 1000 Gigabytes.

That’s the equivalent of over 200 standard DVDs.

Modern computer hard drives are generally measured in either Gigabytes or Terabytes.

A computer hard drive with the top removed to reveal the inside.
Hard drive capacities are usually measured in Gigabytes or Terabytes.

And there are more. After Terabytes, the next one is a Petabyte, followed by Exabytes, then Zettabytes and then Yottabytes.

And by the time you read this, there may even be more because the sheer amount of data that we’re storing on computers is growing out of control.

Megabytes, Gigabytes & Terabytes.

On your home computer, Megabytes (MB), Gigabytes (GB) and Terabytes (TB) are the only sizes you’ll need to know about. At least for the time being.

Bits, Bytes and even Kilobytes are so small that, for the most part, you can simply ignore them. You know about them, and you know what they are, you know they exist.

But the three computer capacities to concentrate on are Megabytes, Gigabytes and Terabytes.

Trying To Remember MB, GB and TB.

Trying to remember what Megabytes, Gigabytes and Terabytes are isn’t that easy if you’re not using them regularly. The words are strange to our ears. They’re not everyday words.

Trying to remember them, and their relationship with each other is difficult. It’s almost a new language.

So let’s see if we can break it down a little.

Firstly, remember that the words change at one thousand. So Mega becomes Giga and Giga becomes Tera at one thousand.

Now one thousand is easy, we’re used to using a thousand. It’s nothing difficult. We can do a thousand.

So what we need to remember is that a Mega, goes into a Giga, and a Giga goes into a Tera.

Megabyte to Gigabyte to Terabyte. And each time the change happens at 1000.

3 buckets, one inside the other and marked Megabytes, Gigabytes, Terabytes.
A Megabyte goes into a Gigabyte and a Gigabyte goes into a Terabyte.

Is It Really 1000, Or Is It 1024?

At every stage so far, I’ve said that when you reach 1000 you change up. So 1000 Kilobytes becomes a Megabyte, 1000 Megabytes becomes a Gigabyte and 1000 Gigabytes becomes a Terabyte.

But if you search the net, or read through some textbooks, you’ll be told that actually, you change up when you reach 1024, not 1000.

So which is it? Well, that depends on who you’re talking to. A human or a computer.

For us humans, 1000 is a nice number. You can easily add or subtract 1000 in your head, no need for pen and paper.

You can even multiply and divide by 1000 without too much trouble.

1000 is a good number to work with.

But that’s because we count in the decimal system.

The amount of Megabytes in 1 Gigabyte and 5 Gigabytes written on a blackboard
Working in 1 thousand is easy to do.

One thousand is a good number because it’s a one and then a few zeros, 1000. It’s nice and neat. There are no straggly numbers on the end to deal with.

Computers, on the other hand, count in the binary system.

Numbers look very different in binary. For a start, you can only have 1’s and 0’s.

Incidentally, that’s why we refer to Bits as ones and zeros.

Let’s take that nice number 1000. Looks good to me and you. We can work with that.

A man working at a computer.
Decimal numbers look very different when written in binary.

But in binary it looks very different. In binary, it looks like this – 01111101000. Not such an easy number now is it? Actually, it’s a bit of a mess.

But guess what 1024 looks like in binary – 10000000000

Now I know there are a lot of noughts, but all the same, you can see it’s a much easier number to work with.

Here are my thoughts on the matter. Whenever you’re counting your Kilobytes, Megabytes, Gigabytes and Terabytes, always change up at 1000.

Don’t worry about the 24 at the end. That’s for the computer to worry about.

And Finally, KB, MB, GB And TB.

Before we wrap up this guide on what are Kilobytes, Megabytes and Gigabytes, I should quickly mention the shorthand (abbreviation) of the words.

When you’re writing the short form of Kilobytes, Megabytes, Gigabytes and Terabytes, always write it with CAPITAL letters.


The capital “B” represents Bytes.

Kb, Mb, Gb, and Tb are not the same. The lower case “b” represents bits.

Kb = Kilobits, Mb = Megabits, Gb = Gigabits and Tb = Terabits.

Blackboard with text.
Bits and Bytes.
Scroll to Top