Get a computer fan that looks good and fits the budget, right? I used to think this way before I dove down the habit hole of computer fans and learned there is more to it than it seems. Who would have thought computer fans came in multiple different sizes.
The size of a computer is perhaps the most important aspect that affects key factors such as airflow, noise level, and static pressure. As a result, it dictates the ambient temperature of the computer.
If all this seems like foreign information to you, don’t worry because, in this article, I am going to tell you everything you need to know about PC fan sizes.
So, without further ado, let’s begin.
What are the different computer fan sizes?
The computer fans come in multiple different sizes depending on the area of application. From the miniature 40mm fans to the more 200mm goliaths, here are the most common sizes of computer fans.
- 40 MM
- 80 MM
- 92 MM
- 120 MM
- 140 MM
- 180 MM
- 200 MM
All computer fans have a square housing meaning that the length and breadth of the fan is the same. For instance, a 120 MM fan measure 120 x 120 MM. With that out the way, let’s go over each of these sizes one and one and discuss them in detail.
40 MM fan
The 40 MM fan is the smallest of the bunch. It is quite thin, with most 40 MM fans coming in at less than 2 inch thick. Due to the sheer small size of this computer fan, it is limited in its application, and it is highly unlikely for mainstream users to come into contact with this size of case fan.
The most common use of this fan is in short-form factor PC cases in which space comes at a premium. In such small builds, 40 MM fans can help create airflow and stop the computer from overheating.
However, by far, the 40 MM is most widely used in hardware cooling applications. Such applications are those in which the 40 MM fan does not serve as the main computer fan but rather acts as a supplementary fan for the cooling of a particular PC component.
For instance, the best example here will be the use of 40 MM fans in X570 motherboards. The X570 AMD motherboard produces a lot of heat. Therefore, the cooling of the computer is not enough to keep the chipset from overheating. So, a 40 MM fan is installed inside the motherboard to cool the chipset.
The 40 MM fans do not provide enough standalone cooling. So, they either need to be used in pairs or at a very high RPM. Since the 40 MM fans are quite tricky, you should only consider getting high-quality fans from reputable manufacturers. I reckon you should check the Noctua NF-A4x10 FLX or the NF-A4x20 PWM.
80 MM
The 80 MM fan is a step up from the 40 MM fan both in terms of size and cooling. Unlike the 40 MM fan, this fan provides enough cooling that it can be used as a standalone fan.
Many small form factor and home theater PC cases (HTPC) support this fan size. In fact, 80 MM fans are the most widely used fan size for HTPC builds.
The 80 MM fan has also found a way into the OEM workstation desktops of Dell and HP. Their ability to be mass-produced cheaply and easily has made them very attractive to these mainstream tech companies. Some CPU air coolers also use 80 MM fans, but this applicator of the 80 MM fan is somewhat limited.
When talking about good recommendations for 80 MM fans, there are many options to choose from, but again, the safest choice will be the Noctua NF series, which comes in both a performance and a quiet version. I would also like to give an honorary mention to Bequiet Pure Wings 2 for being near silent in use.
92 MM
The 92 MM fan size sits in limbo – it is not too large enough that it breaks the tripe digit measurement, nor is it small enough for use in mini-ITX builds. Since its sits in a weird place, it is not used and often overlooked.
That being said, there are a couple of applications where this fan size is useful. For instance, some OEM manufacturers like to use the 92 MM fan size in their proprietary PC cases. There are also a handful of CPU air coolers that accept the 92 mm fan size.
Suffice to say, 92 MM computer fans may have fewer applications. However, there are multiple options available at your disposal. Besides the usual Noctua NF series, other 92 MM fans I will recommend trying are Scythe Kaze Flex and SilverStone Air Slimmer 90.
120 MM
The 120 MM computer fan is perhaps the most widely used case fan size. They are used in almost all sorts of different applications, and they are also the default choice for many less tech-savvy PC builders looking for a computer fan.
The main reason for the popularity of 120 MM fans is the fact that they are very versatile and can pretty much perform well in any situation. They can be deployed as case fans, CPU fans, radiator fans, etc, and used interchangeably among these different applications.
Almost all standard PC case sizes have support for the 120 MM fan.
Such versatility appeals to consumers that want a computer fan that can get everything done. There are countless good 120 MM fans that have stood the test of time; among them include my favorite Corsair LL120 RGB fans.
140 MM
The 140 MM fan size is the second most popular computer fan size. This fan size is also used for a wide variety of different applications. The 140 MM fan can fit in all standard case sizes, including the full tower, mid-tower, and mini-tower.
Since the 140 MM fan is larger in size compared to the 120 MM fan, it can produce the airflow as the 120 MM fan at a lower RPM. Hence, they are quieter as well than the 120 MM fans. However, more often than not, you will see them being used interchangeably with the 120 MM fans in the same computer.
I have been trying out my 140 MM fans for my PC builds and have found the Be quiet! Light Wings to work best.
180 MM
The 180 MM fan size is quite rare and not used much in mainstream applications. This fan size is not supported by AIO liquid coolers, which limits its use. Most PC cases are also not made for the installation of 180 MM fans.
Another reason for their lack of popularity is the fact that there are only a handful number of companies that sell these 180 MM fans. So, the options for the consumers are few and far, which results in people gravitating towards other computer fan sizes like 120 MM or 140 MM.
200 MM
The 200 MM fan is the largest computer fan. Compared to the other fans, it is massive, and due to its enormous size, the 200 MM does not need to spin at a high RPM to produce airflow.
The 200 MM fan size was made popular by Cooler Master when they started installing this fan in their airflow cases. Due to its effectiveness of pulling massive amounts of air into the case, many other companies jumped on board and started selling 200 MM fans.
Today, there are numerous 200 MM available in the market. However, the original design from Cooler Master in the form of the MasterFan MF200R RGB still leads the way in terms of performance.
How to measure computer fan size?
Have fans in your PC that you want to know the size of? Don’t worry, we are going to take a look at how you can measure the fan size using simple tools and techniques.
There are two methods that you can use to measure the fan size. For any of the methods to work, you will need a measuring tape and a Philips head screwdriver.
Method 1: Measure the fan from edge to edge
The first method is pretty self-explanatory. You can determine the fan size by measuring from one edge to another. The measuring tape can be placed either along the horizontal or the vertical edges. Do not measure the fan diagonally, as it will give you a false reading.
Most measuring tapes are in inches or cm, so to get the actual fan size, you will need to convert the value into mm.
Method 2: Measure the distance between the screw holes
If you cannot figure out the length of the fan, or perhaps the fan is absent in a particular area of the case, then you can measure using the screw holes.
The fan attaches to the PC case using screws. As a result, every PC case has screw holes that you can measure to determine the fan size. The screw holes are measured in a similar fashion as the fans. You either measure horizontally or vertically and not in the diagonal direction.
Note: The distance between the screw holes does not correspond to the exact size of the fan. The distance between the screw hole is slightly shorter than the actual fan size. For reference, use the chart below.
| Fan Size | Screw Hole Spacing |
| 40 mm | 32 mm |
| 50 mm | 40 mm |
| 60 mm | 50 mm |
| 70 mm | 60 mm |
| 80 mm | 71.5 mm |
| 92 mm | 82.5 mm |
| 120 mm | 105 mm |
| 140 mm | 124.5 mm |
| 200 mm | 154 mm |
| 220 mm | 170 mm |
Fan size and screw hole spacing table from Voltcave
What are the effects of the different computer fan sizes?
The size of the fan can have a significant effect on the airflow, static pressure, and noise levels.
Airflow
Airflow is perhaps the most important term that is synonymous with cooling. Not all fan sizes produce the airflow. Generally, the larger the fan size, the more airflow it will produce.
Airflow is measured in cubic feet per minute (CFM), which essentially determines how much air a fan is displacing in a given minute. If we take a look at the CFM values, we will notice a trend. As the fan size increases, the CFM value also increases.
For instance, the Corsair LL120, a 120 mm fan, has a CRM value of 43.25. In contrast, the CoolerMaster Master Fan MF200R has a CFM value of 90. Based on this, we can witness an airflow increase of 208% by jumping from a 120 mm fan to a 200 mm fan.
That being said, chasing only after a high CFM value and racking up large fans is not effective for airflow. There are many other factors besides airflow that constitute a good cooling system in this case. So, if they are absent, the effect of airflow on cooling is negligible.
Static Pressure
The static pressure is the air pressure created by the fan. Air flows from a region of low pressure to a region of high pressure. Therefore, maintaining a positive high-pressure environment for the exchange of air inside and outside of the PC is important.
The fans create a static pressure zone near the case, which helps create high air pressure resulting in the air moving toward the case. Static pressure is very important to overcome obstacles such as filters and radiator fins.
Therefore, for AIO liquid coolers, high static pressure fans as a better choice than fans with high airflow (CFM). Generally, the smaller the fan size, the higher the static pressure. However, you also don’t want a fan that is too small because then it would be able to provide airflow. Essentially, there must exist a sweet spot between airflow and static pressure for the most optimal cooling performance.
Fan Speed (RPM)
The fan speed is measured in revolutions per minute (RPM). The size of the fan has a direct impact on the fan’s speed. Generally, smaller fans spin at a higher RPM, while larger fans spin at a lower RPM.
Since the smaller fans do not have much airflow, they need higher speed to produce effective cooling. On the contrary, large fans can generate much higher airflow, so they do not need to spin at higher RPM.
Noise Level
The noise level varies from fan to fan, but it would suffice to say that as the fan size increases, the noise levels also increase. Essentially, larger fans have a much larger volume. Trying to spin a large object requires more force because they have greater inertia creating higher friction and noise.
The large fans also dissipate higher cubic feet of air with a single sweep than a small fan. So, that is another reason for the higher noise level. That being said, the noise level is also majorly dependent on the RPM of the fan. As the RPM increases, the noise level also increases.
Conclusion
There is a lot to know about computer fan sizes, and after reading this article, you know all of the important stuff. Always remember, there is no right or wrong size when it comes to computer fans. They are all equally viable in the right situation.
That being said, it is not easy to make a choice of which fan size is right for you. So, whenever you are hesitant, always opt for the 120 MM or the 140 MM fan size because they can fulfill any given requirement.
