The Different PC Case Sizes Explained: From Full Tower to Mini ITX Cases

PC Cases may look quite similar, but there are a wide variety of different sizes and styles that can be difficult to spot when hunting for an upgrade or starting a fresh build.

For a long time, the categories for cases weren’t easy to understand and different brands and manufacturers often changed their specifications and sizes while using various different designations which caused a lot of uncertainty across the industry. 

The Different PC Case Sizes Explained

While this remains a small problem as the designs of different manufacturers change and develop, there are at least a few established size categories that can help customers and businesses to find cases that will work for their intended componentry and workspace.

In this article, I’m going to look at the different motherboard sizes and explain a little about why this is important to case design, before highlighting the specific size tiers and what sets them apart while looking at some of the pros and cons of each type.

Motherboard Form Factors

One of the key factors in deciding on a style of case is to determine what size motherboard you have or plan to use.

There are a few different types of motherboards and each one has various advantages and disadvantages as well as various features that make them suited for their particular role.

When looking at motherboards it’s important to make sure they are compatible with your other components as there are very specific and minute differences between versions that make them compatible with various CPUs, graphics cards, and cooling setups.


ATX boards are some of the most common motherboards and are typically known as ‘full size’ motherboards.

They measure roughly 12-inch x 9.6-inch or 305mm x 244mm and are capable of handling most of the main components available to enthusiasts, and can often support more than one GPU linked through Crossfire or SLI.

ATX motherboards are some of the most feature-rich and are used extensively due to this.


These boards are a little smaller than their big brother, the ATX full-size board, measuring 9.6-inch x 9.6-inch or 244mm x 244mm.

This smaller size comes with a host of benefits, such as reducing the size and profile of your PC, using less space in the case, and often being much more streamlined and cheaper than full ATX boards.

However, these smaller boards tend to drop some features and compatibility in order to slim down.

That being said these boards are an excellent compromise and work well in most systems, and are compatible with most hardware in various formats.


Mini-ITX boards are some of the smallest available and fit into a fraction of the space ATX and mATX boards take up, measuring just 6.7-inch x 6.7-inch or 170mm x 170mm.

This allows these boards to fit into very small cases allowing customers to make much more portable builds or fit their systems into cramped workspaces.

However to shrink down to this size these boards drop a lot of benefits the other boards have and also tend to lack space for as many upgrades and parts.


Extended ATX boards are actually the biggest motherboards available outside of server focussed/specialist motherboards, measuring 12-inch x 13-inch or 305mm x 330mm.

This means that many enthusiasts have a hard time finding reasonable cases to fit these motherboards into, and although their added size does allow for more features, a lot of enthusiasts find these features to be extraneous and seldom worth the added size of these larger boards.

This explains why ATX and mATX boards are the go-to options, they offer a sweet spot in terms of size, features, and compatibility.

Tower Sizes

Now that you understand the different size motherboards we can get into PC cases and what the different sizes mean.

Small Form Factor (SFF) (Mini-ITX)

These cases are quite simply the smallest PC cases in the world, capable of being highly portable and easy to fit into cramped workstations. This makes them popular in workplaces and even as entertainment hubs that allow home users to hide their multimedia setup in a cabinet quite easily. 

These are also suitable for LAN parties due to their reasonable size and weight. 

While this style of case isn’t the most popular there are definitely applications for it among certain niche groups, and they offer something different for the space-strapped customer.

Be warned however that airflow inside these small cases is very poor which can make temperatures higher and can stress your components or lead to throttling without adequate cooling solutions.

Also, these smaller cases are very difficult to work in when it comes to fitting or adjusting components, and they also limit the flexibility you have when it comes to what components you can use.

Mini Towers (MicroATX)

The next size up is the MINI tower, which is actually growing in popularity and competing with the most popular case sizes.

This increased popularity is due to a few different factors, such as their competitive pricing,  flexibility, and ability to use various componentry while remaining quite portable and small. 

Their compatibility with MicroATX boards is a massive bonus, as these motherboards offer excellent value for money, meaning many budget-conscious builders turn to this form factor in order to save space and money without losing out on performance. 

While the small size allows these cases to fit into small spaces, they do have drawbacks similar to SFF cases, but they just aren’t quite as severe.

The smaller interior makes fitting and cleaning your PC much more awkward and difficult, and you are limited in what you’re able to cram inside both in terms of motherboard slots and actual space inside the case.

These cases are also prone to getting hot and require very good cooling to ensure that components are able to provide their best performance without throttling or getting damaged.

Setting up water cooling may be possible depending on the case, but even if you go for air cooling special care should be taken to help make airflow as efficient as possible.


Mid towers are the most popular case size and were the traditional size of computers before everything began to shrink down in size.

While its little brothers have many excellent benefits, the Mid Tower remains a favorite among enthusiasts due to its flexibility, efficient cooling, excellent cable management, and its ability to fit far more equipment.

These cases are capable of taking both ATX and mATX boards which gives users plenty of choices when it comes to motherboard options.

They also have ample space for large high-performance components such as graphics cards, and can even manage to hold more than one for users who want a dual graphics card setup. 

They can handle all of this while still keeping airflow consistent and often have space for more comprehensive cooling setups such as water cooling and beefier fan towers, as well as more options for case fan placement. 

Cable management in these cases is a breeze and they have many superb tools for keeping everything neat, such as cable runs, drive sleds, and rubberized cable holes to prevent damage and wear on your wiring.

They also have excellent expansion capabilities and can fit optical drives as well as various storage devices. 

Their size and space also make them much easier to work inside of and easy to clean as it’s easier to see what you’re doing and where everything is located.

Their drawback is of course that they take up a lot more space and are far less portable than some of the smaller platforms

Full Tower/Extended ATX (E-ATX)

Full towers are not as very popular among the majority of PC users, mainly due to the law of diminishing returns.

These cases offer a supreme amount of space for a staggering amount of parts and also provide superb airflow capabilities. 

Able to fit the massive EATX motherboards, these cases are a favorite of overclockers and hardcore gamers who want to pack as much performance as possible into a single case.

These cases are also used to accommodate servers alongside a standard pc system and are able to accommodate the biggest and best components available, along with the most elaborate and high-performance cooling systems. 

The obvious drawback is of course the sheer size of these cases and their total lack of portability.

Stephen Deane

Stephen is a gaming and tech enthusiast. He has been playing computer games since the Commodore 64 days in the 80s. He has worked as Broadcast Engineer with BBC News and knows a thing or two about building, fixing, and playing with PCs.