GB vs. GiB: The Difference in Bytes


GB vs. GiB: The Difference in Bytes

Sometimes, it feels like computer jargon sets out to confuse you. If you’ve managed to figure out the difference between a bit and a byte, but you’re still scratching your head over GB and GiB, you’re not alone. While it might seem at first that these terms might be equivalent, or even that it’s just a typing error. However, this isn’t the case. Both gigabytes (GB) and gibibytes (GiB) are used as units of measurement, particularly for computer data. Yet once you move past the kilobyte (KB) stage, the size differences increase significantly and are no longer negligible. When paying for storage devices, new PCs or file transfers, it’s beneficial to understand the distinction. Let’s take a deeper look at GB vs. GiB.

GB vs. GiB: Side-By-Side Comparison

Unit StyleMetricNon-metric
What It IsUnit of data equivalent to 109 (or 10003) bytesBinary unit of data equivalent to 1.0749 (or 10243) bytes
How It’s UsedMetric system of measurement, reported size of RAM or storageUnit of measure used in computing

The History Behind GB and GiB

At first glance of the table, it might look like there’s not much difference at all between GB and GiB. Certainly, in the case of kilobytes (KB) and kibibytes (KiB), which are equivalent to 1,000 bytes and 1,024 bytes respectively, the difference is minimal. As data capacity increases, however, it does become significant — there’s a 7% difference in size between a GB and a GiB. This is because data capacities tend to increase exponentially; the size of a GB is equivalent to the size of a KB cubed. You’d be forgiven for thinking this is complicated because essentially, it is! It helps to have a look at how this distinction came about to understand it more deeply.

How Computers Use Data 

Computing systems operate using binary data, with their data measured in binary code. Binary data basically means data that only consists of 1s and 0s, and the binary number system is where the prefixes “gibi”, “kibi” etc come from. As such, these names are used to reflect the systems in which they’re used. 

GiB and other binary-based units are measured in base-2, meaning they’re measured as powers of the number 2. For example, a GiB is 10243 as previously mentioned, which is equivalent to 230 bytes. In other words, 2 multiplied by itself 30 times. This is different to a GB, which is measured in base-10. You might’ve figured out that this means powers of the number 10. As such, a GB is defined as 109 bytes, or 10 multiplied by itself 9 times. A GB is therefore equal to 1,000,000,000 bytes, and a GiB is equal to 1,073,741,824 bytes. You can see from this that there’s around a 7% difference in size.

binary operator
Binary is the basic language of computing systems. This is a base-2 numeral system, which uses only two symbols: 0 and 1.

©Pixels Hunter/Shutterstock.com

The Origins of GB

It might seem strange that just 30 years ago, GiB wasn’t even a recognized unit. Before the GiB was defined, data was classified according to the pre-existing metric system units (kilo, giga, mega, tera etc). This is a decimal-based measurement system, with units such as centimeters and meters, milliliters and liters, and grams and kilograms. As such, data capacities were initially called kilobytes, gigabytes etc to reflect the metric units.

Strictly speaking, a binary kilo was never equivalent to a metric kilo, but the difference was so minimal that engineers often used the terms interchangeably. And this was mostly fine because they knew the differences. Memory capacity was capped at the kilobyte level, so the discrepancy was only ever 2.4%.

The Introduction of GiB

As data capacity progressed a lot quicker than many technology experts could’ve imagined, the discrepancy in data increased substantially. To try and fix this, the International Electrotechnical Commission (IEC) introduced a new standard of measurement with binary prefixes. This meant GB retained its original metric definition of 1,000 bytes, and the new GiB referred specifically to the binary definition of 1,024 bytes. 

Real-World Consequences of GB vs. GiB

You’d be forgiven for thinking this is all a bit complicated since they did essentially change the definition of a GB before changing it back again. To make matters worse, there’s no legislation dictating the use of these terms, so companies can and do use whichever they wish. There have even been lawsuits in the past where people thought they were being misled and duped by tech companies. 

This can also lead to confusion when there’s a difference in operating systems. Whereas Apple recently changed their systems to display 1000MB as 1GB, Windows opts to display 1,024MB as 1GB instead. In actuality, 1,204MB is 1GiB. This accounts for differences in file size when transferring between the two systems. It’s fairly common for users to think a file has been corrupted or data lost because the size decreases when transferring from a Mac to a Windows PC. Really, though, the file is absolutely fine, it’s just that the unit of measurement has changed.

GB vs. GiB: Why You Should Know the Difference

Aside from not being worried about the safety of your files, there are some other practical reasons for understanding this difference. Firstly, you might not be getting as much data as you bargained for when purchasing a storage device. Companies tend to artificially inflate these capacities by listing them as a metric GB, whereas the computer actually reads them as GiB. In this way, a 500 GB hard drive will end up actually only being around 485 GB.

A similar thing happens with a 2TB drive, which will end up displaying 1.8TB of storage instead. This also means that a 500GB file from a Windows PC won’t actually fit on a 500GB hard drive. Technically, the drives are as large as they’ve been advertised, it’s just that operating systems measure them in a different way. And of course, a higher and rounded number usually sells better than an odd number that’s smaller.

Where RAM is concerned, however, the advertised GB is actually equivalent to GiB. This is because RAM is often available in multiples of 8, and GiB are all divisible by 8 since they are powers of 2.

The other situation where you might want to be aware of the distinction is when it comes to paying for large file transfers. If the company you use charges per GB, then you’ll end up paying a lot more over time than one that charges per GiB. This is due to the fact that 1GB is equivalent to less than a whole GiB, so you’d appear to be transferring more data.

File Transfer Protocol (FTP) graphic
When paying for large file transfers, note whether the company charges per GB or GiB. You would pay less in the long run per GiB.


GB vs. GiB: 6 Must-Know Facts

  • Gigabyte abbreviates to GB, and Gibibyte abbreviates to GiB
  • A GiB is larger than a GB
  • 1 GiB is equivalent to 10243 bytes, whereas 1 GB is equivalent to 10003 bytes
  • GiB is measured in the base-2 binary system, whereas GB is measured in base-10
  • Computing systems read, store and use data in GiB rather than GB
  • Windows PCs report GiB as GB, so the practical storage capacity will appear less than advertised

GB vs. GiB: Which One is Better? Which Should You Choose?

In the strictest terms, there’s not really a contest between GB and GiB, nor much choice. This is because your computer will always store and use data in GiB form, even if it displays as a GB. You can’t exactly dictate how the storage will be advertised whenever you’re buying a product, either. However, if you know and understand the distinction between a GB and GiB, you can avoid being unpleasantly surprised by storage capacity, as well as make smarter decisions regarding paying for file transfers.

Up Next…

GB vs. GiB: The Difference in Bytes FAQs (Frequently Asked Questions) 

What's the difference between GB and GiB?

In simple terms, a gigabyte (GB) is defined as 10003 (1,000,000,000) bytes, whereas a gibibyte (GiB) is defined as 10243 (1,073,741,824) bytes. Therefore, 1GB is equal to 0.93GiB.


Why does GB vs. GiB matter?

When you’re buying a 500GB hard drive, for example, the actual capacity is lower since computers store and use data as GiB. This can also impact transfer time, as well as costs when paying for file transfers.

Is memory measured in GB or GiB?

RAM is measured in base-2 GiB, since both are divisible by 8. However, it’s still incorrectly called a gigabyte. Storage, on the other hand, calls it a gigabyte, but it’s actually stored and used as gibibytes.

Which is bigger, GB or GiB?

1GiB is larger than 1GB, because it’s equivalent to 10243 bytes, as opposed to 10003 bytes.

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