Are All Motherboards the Same Size?

The answer to the question “are all motherboards the same size?” is a resounding NO, not all motherboards are of the same size. Motherboards can vary drastically in terms of their physical dimensions.

Some are small, whereas others are large. There is no universal motherboard size.

The size of a motherboard is described by its official form factor standard. There are different motherboard form factor standards such as ATX and Mini ITX etc.

The size of the motherboard can have several ramifications on the way you build your PC. For instance, smaller motherboards can fit in compact cases and they do not have much expansion capability.

Larger motherboards, on the other hand, require larger PC cases and offer greater degree of expandability.

In the following text I will talk in detail about the different sizes of motherboards, what they are called and what their purpose is.

What is Motherboard Form Factor?

Motherboard form factor basically defines the physical shape and the dimensions of the board itself.

Form Factor of a motherboard is named based on the standard it follows. There are two common standards used: ATX and ITX.

ATX was developed by Intel in 1995, where as the ITX form factor was developed by VIA Technologies in 2001.

These standards are designed in order to maintain the interchangeability of different parts of a computer such as the power supply, the ports, the case that it goes into etc.

Both the ATX and the ITX share many similarities such as the main motherboard and the CPU power connectors as well as the expansion slot.

However, while ATX is the most common standard used for motherboards, ITX, on the other hand, is used for compact and mobile computers.

There are Three Common Commercial PC Form Factors – One for Workstation

Now both ATX and ITX standards are divided into several different form factors such as Standard ATX, mATX, Mini-ITX, Nano-ITX, Pico-ITX, Mobile-ITX etx.

However, for commercial PCs there are three common form factors i.e Standard-ATX, mATX and Mini-ITX. Workstation PCs, on the other hand, often use the E-ATX motherboards.

The following table defines how these form factors differ in terms of size and purpose:

Form FactorDimensionsPurposeRemarksNo. PCIe Slots
(aka Full-ATX
Standard ATX)
12 x 9.6 inches
305 x 244 mm
Commercial- For Gamers and Professional
- Fairly common
- Best expansion capability for commercial purpose
2-3 x16
2-3 x1
Micro ATX
(aka mATX)
9.6 x 9.6 inches
244 x 244 mm
Commercial- Feature affordable motherboards
- Moderate expansion capacity
1-2 x16
1-2 x1
Mini ITX6.7 x 6.7 inches
170 x 170 mm
Commercial- Smallest motherboards or PC
- Minimal expansion capacity
- Expensive due to their compact design
1 x16
Extended ATX
(aka E-ATX)
12 x 13 inches
305 x 330 mm
Workstation- Intended for workstation builds
- Expensive and compatible only with specialized workstation CPUs.
4-7 x16

Also Read: Where is the Motherboard Located in a Computer?

Let give me a brief about each of these form factors.

ATX – aka Full ATX – aka Standard ATX – Most Common

ASUS Prime Z690-P D4 ATX
ASUS Prime Z690-P D4 ATX motherboard. Source: Newegg

These are the largest and the most common motherboards for commercial PCs. 

As such, depending upon the chipset they feature, they have the highest expandability options.

They often feature 2-3 PCIe x16 slots along with a few PCIe x1 slots, 4-6 SATA slots, support for a higher amount of RAM, multiple M.2 slots and plenty of fan headers for cooling.

ATX motherboards are often used by gamers and professionals  on their mid and full tower PC cases. They also readily support multiple GPUs and NVIDIA SLI in particular.

As far as the price is concerned, the ATX form factor varies drastically ranging from $99 all the way to $900.

Of course there is a multitude of factors that goes into determining the price of a motherboard, and the form factor is one of them.

Read in Detail: How Much is a Motherboard?

Micro ATX – aka mATX – Budget Friendly

ASUS Prime Z690M-Plus D4 Micro ATX
ASUS Prime Z690M-Plus D4 Micro ATX motherboard. Source: Newegg

mATX is considered as the budget friendly form factor.

If you are planning on building an affordable PC, then mATX is what you should be looking at.

mATX motherboards, compared to ATX motherboards, offers fewer expansion slots. They can have a maximum of 2 x PCIe x16 slot and one or two PCIe x1 slots. 

They have a fewer number of M.2 slots on average and also a fewer number of RAM slots – albeit the mid range and the high end mATX motherboards offer as much RAM support as ATX motherboards.

These are great for a Mid Tower or a Mini Tower build as they would look very odd in a Full tower case. 

Depending upon the chipset and the configuration of the motherboard, mATX can cost anywhere between $80 all the way to $350.

Mini ITX – For Compact PC Builds

MSI MEG Z690I UNIFY Mini ITX Motherboard

Mini ITX motherboards are the smallest commercial motherboards that you can build a PC with.

There are smaller still form factors such as Nano-ITX and Pico-ITX but you cannot build a conventional PC with them. They are more specialized.

Mini ITX motherboards are great for compact PC builds. These can fit in Small Form Factor (SFF) PC cases, most of which can be carried around easily.

The biggest issue with Mini ITX motherboards is that their expandability is highly limited. As far as PCIe slots go, they only feature a single PCIe slot and nothing more. They also often have only two RAM slots and a single M.2 slot.

Since they do not feature any PCIe x1 slot for the option of installing a WiFi Card, they often come with built-in WiFi.

They are also not the cheapest motherboards. Due to their novel compact design, they are actually quite expensive, starting at about $150.

EATX – aka Extended ATX – For Workstation Builds

ASUS ROG Maximus Z690 Extreme Glacial EATX
ASUS ROG Maximus Z690 Extreme Glacial EATX motherboard. Source: Newegg

Finally we have the EATX motherboard.

These are actually larger than ATX motherboards. However, they are not really intended for commercial PCs.

EATX motherboards are often used in professionals workstations or by the wildest games and enthusiasts out there.

So Are All Motherboards the Same Size?

It should be quite clear by now that motherboards are NOT all the same size. They vary drastically in size depending upon their form factor.

If you are unsure about your motherboard’s form factor, then I have written a detailed article on how to figure that out:

Of course different motherboard sizes require different PC case sizes. For instance, an ATX motherboard cannot fit in an SFF or a Mini Tower PC case.

Do All Motherboards Fit in Any Case
Motherboard sizes inside Full Tower PC case. Source: FXCustomPC

Read in detail: Do All Motherboards Fit in Any Case?

In addition to that, different motherboard form factors also have their screw holes in different position. You then have to position the standoffs on the motherboard accordingly.

Also Read: What are Motherboard Standoffs?

What is the Best Motherboard Form Factor to Get?

This is a fairly open ended question and in reality it all depends upon your budget and your taste. There is no one answer-fit-all scenario.

After all, there is a reason why the different form factors exist.

Standard ATX motherboards have the perks of having a high level of expandibility. They would look great when fitted into a full tower case – the size many gamers and enthusiasts prefer.

Micro ATX motherboards are great for a budget PC builds. Office or home users should look into micro ATX motherboards. They are also great for a semi-compact build with a Mini-Tower PC case.

Mini-ITX, while expensive, are great for a compact build. When installed into an SFF PC case, they can actually be carried around. So you can literally build a gaming console of your own with a Mini-ITX.

Finally, we have the EATX. If you are considering getting an EATX motherboard, then chances are that you are already very well versed with your needs anyways since EATX is not intended for an average Joe. EATX motherboards are expensive but they are the basis for many high end workstations or for the craziest gaming rigs.

So in short, the best form factor for you is that which fulfills your needs the most and fits in your budget.

Final Words

Again, the answer to the question “are all motherboards the same size” is a no. There is no universal motherboard size.

There are, however, only a handful of motherboard form factors that you need to be aware of for the purpose of PC building i.e ATX, mATX and Mini-ITX.

Also Read: Can You Upgrade a Laptop Motherboard?

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Atif Qazi
Atif Qazi is the founder of PCGuide101 and an expert in the computer peripheral industry with over two decades of experience. He has worked as a consultant for major companies and has a deep understanding of the inner workings of computer peripherals. He has a degree in Electrical Engineering and has served as a product manager and technical consultant. He is passionate about testing and evaluating the latest products to provide readers with reliable information.

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