140mm vs 120mm Case Fans

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What are the main differences between 140mm vs 120mm case fans? The biggest difference between a 140mm and 120mm fan is the size. This crucial factor can affect several pieces of the fan including: performance, noise, and fit.

There can be several other differences between the very common 140mm vs 120mm fans. But, no need to worry, today I’ll be going over everything you need to know.

Trust me, I’ve been there before. You are looking to build your next performance gaming PC. But, you didn’t know what fans to get, so you looked at my guide to the best RGB fans. Then, you found what brand of fans you wanted, but what size/type should you get for your case? What are the differences between 120mm and 140mm fans?

Those are the exact questions I’ll be answering today. But, with that being said, let’s get into it!

140mm vs 120mm Fans Differences

There are several differences between the 140mm and 120mm fans besides size. Today I’ll be comparing the two. The comparison is derived from the Corsair QL120 and QL140 fans.

They are some of the best case fans on the market and are a good relative comparison.

140mm Fan

  • 140mm x 140mm x 25mm
  • 6V-13.2V
  • 0.234 LBS
  • 1.4 mm-H20
  • 50.2 CFM
  • 26 dBA
  • 550 – 1250 ±10% RPM
  • Around $5 more (subject to change)

120mm Fan

  • 120mm x 120mm x 25mm
  • 6V-13.2V
  • 0.171 LBS
  • 1.55 mm-H20
  • 41.8 CFM
  • 26 dBA
  • 525 – 1500 ±10% RPM

As you can see, there are some significant differences between the two sizes. Mainly these differences include the weight, static pressure, flow amount, and speeds.

I do want to point out that the rated decibel or sound levels of these two fans are identical. However, this is not the case with all fans.


The size is a pretty obvious difference. But, there are many applications where you cannot use 140mm. For example, a 360mm radiator will only accept 3x 120mm fans. You will not be able to use 140mm fans. And, vice-versa with a 280mm radiator. You can only use 2x 140mm fans.

Additionally, there are often different cases that will only accept certain types of fans in certain locations. There can vary greatly based on what PC chassis case you are choosing, so you’ll have to go over those details when choosing.

Static Pressure

The static pressure of these fans can play a big role in which one to put into your next build. The 120mm fan size has a higher static pressure at 1.55 mm-H20. This means that they are more ideal for radiators that require high static pressures.

Additionally, if you are using a specific flow direction/static pressure map for your PC, then you might want to carefully choose what you’d rather have (source).

Flow Amount

The flow amount plays right into static pressure. Inversely, you might want a higher flow rate (CFM), which case you’d probably go with the 140mm fans. These have big blades that push a lot of air. While they spin at slower speeds, they can push larger amounts of air with lower speeds.

50.2 CFM is a lot of air flow and if you are optimizing your case for pure push of air, then the 140mm fans are the way to go.


Speed is again related to flow rate. You’d think the faster the fan spins, the higher the flow rate. However, the 120mm fans are faster, but have a lower rate. This is due to the fact that the blades are smaller. While this can be a big factor for static pressure, flow rate is drastically affected by the blade size.

The speed is huge for determining which fans you want where. Depending on if you can control your fans speed can play a big part on where you are plugging them in. Additionally, it can be tough to decide between a bigger or smaller fan based on speed alone. Using all of the contributing factors, you can determine between a 120mm vs 140mm fan size.


Finally, we get to the noise of the fans (or decibel rating). While the two fans in our example have the same decibel level, this is not the norm.

Typically larger fans have larger blades, and push more air. Although, the smaller fans have a faster operating speed. So, which one is louder?

Often a bigger fan will be a bit louder than their smaller counterparts. This can vary greatly between fans based on their speed, blade size, and blade count. Additionally, manufacturers such as Noctua place significant emphasis on operating volume.

So, there isn’t a clear cut answer for every fan. It will be up to you to determine what volume is acceptable to your ears.

Are 140mm Fans Better Than 120mm?

140mm fans are typically stronger, more powerful and obviously bigger than 120mm fans. While these can be important attributes, that does not necessarily mean they are better. There are a lot of applications that PC builders might require a 120mm over a 140mm fan, especially when there is tight fits.

Another big point when it comes to size comparisons is in the price. Bigger fans cost more, making it harder to fill your case with fans (if you are ballin’ on a budget).

But, if your PC and budget have the room, there really isn’t a reason not to fill it with 140mm fans.

Can You Mix 120mm and 140mm Fans?

Of course you can mix 120mm and 140mm fans. There are no rules saying that you cannot have both in your case. However, you shouldn’t mix 120mm and 140mm sizes when using an AIO coolers/radiator. Or, in certain cases of performance with static pressure.

You have to be sure you know what directional flow of air you want, along with where you want positive and negative pressure areas.

120mm vs 140mm Fan RGB Lighting

Typically there are no differences between 120mm vs 140mm fans in regards to RGB lighting. Both fan sizes often have the same options for lighting.

However, with a bigger fan, you most likely will have more LED’s or at least a brighter light signature. This can play a vital role if you want the brightest fans you can get!

Final Thoughts: What is Better 140mm or 120mm?

In conclusion, what should you get a 140mm vs 120mm fan? In my opinion, there is no clear winner. 120mm fans are a more popular option due to their more compatible size and accessible price-point. However, both fan sizes have valid applications.

There are some situations that you want a 140mm fan in, and some that you want a 120mm fan in. The final answer is, it just depends.

Whatever you end up getting, we can help you along the way. Check out my lists that include the best budget RGB fans, and best premium RGB fans.

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