120mm vs 140mm Fans: The Complete Guide
Ah, cooling, it’s easy to spend hours obsessing over what the best setup is to reduce your PC temperatures just that little bit more.
One of the most important aspects is what arrangement of 120mm & 140mm case fans you install.
But which kind of setup is better?
Today’s feature is here to explain everything you want (and need) to know for 120mm vs 140mm PC fans; comparing noise, performance, size, and price.
We’ll also go over the best case fans for your next build, too!
Table of Contents
Differences Between 120mm & 140mm Fans – Short Answer
We’ll discuss each of the main comparison areas in depth below.
But if you’re after the TLDR; on average, builds based on 140mm fans are superior to 120mm fans.
They tend to perform more quietly in comparable operations, offer slightly better cooling & are cheaper when considering you need to buy less of them to perform.
But, and it’s a big but, it hugely depends on the quality of the fans in question.
A good 120mm fan will be better than a mediocre 140mm fan, etc.
It also depends on the PC case you’re using and what it allows; we wouldn’t say that 140mm fans are so superior that you shouldn’t get a certain type of case if it has more allotment for 120mm cooling.
Unless you’re very focussed on min-maxing cooling, we’d instead advise you to focus more on which PC case you want; which is why we’ve included the best 140mm and 120mm fans throughout this feature.
Overall Best 140mm Fan: Noctua NF-P14
This flagship fan from one of the best brands in the PC cooling business has been through countless iterations.
While we recommend other options below for RGB, premium, silence-focussed, or budget users, the NF-P14 strikes the best sweet spot between decent airflow and a wonderfully low price.
Overall Best 120mm Fan: Noctua NF-P12
Thankfully, as with most of our top picks on the list, if a brand has made a great 140mm fan, they’ve nearly always come through with a 120mm version that is of the same quality (relatively).
The P12 is no exception; with excellent CFM for the price, it’s a perfect mid-range option.
120mm vs 140mm Fan Cooling
There are a few miscellaneous factors like bearing type that determine the finer aspects of a fan’s performance, but by far the two most impactful specs (and the ones you should focus on) are RPM and CFM.
CFM, or cubic feet per minute, is the amount of air a fan can move per minute and the most important spec when establishing cooling capability.
Most benchmarks and tests show that the average 140mm fan, with its longer blades, tends to boast a significantly higher CFM rating and can produce better airflow in a case per-fan compared to 120mm offerings.
Things other than mm size can affect the CFM, like blade design, material quality, and most notably RPM.
RPM, or rounds per minute, is how many times a fan can spin per minute.
So for example, if you had two fans identical in every way other than their RPM, the higher RPM fan would be able to produce better CFM.
Generally speaking, 120mm fans often (but not always) have slightly higher RPMs if we’re comparing the same 120mm/140mm models.
This is to ensure they don’t fall too far behind the high airflow/CFMs of 140mm offerings, which can run at lower rounds and achieve the same as a 120mm fan working harder.
So with all that said, we still rate the performance of 140mm fans as the best in most situations, but 120mm can still be a great ally if your desired case focuses on them.
As always, quality matters most.
We’ve seen other resources say 120mm/140mm fans go up to ~1,500 RPM, and this is very far from the truth.
The range is huge; for mainstream choices, fans in either size tend to vary from around 600rpm to 3000rpm, but for some crazier offerings they can go as high as 10,000 (not that you need this, they’d sound like a jet engine too!).
Conclusion: 140mm fans are usually the better choice for airflow if your build allows it. But if not, don’t fret; you can still get great cooling done with 120mm offerings, what’s most important is picking high-quality fans in either size and a chassis that facilitates good airflow.
While CFM/RPM is where the main difference occurs between 120mm/140mm head-to-heads, we wanted to touch on a spec that is very important for certain placements.
Static pressure is the rating a fan gets which, in simple terms, dictates how much of the airflow/CFM produced will penetrate heatsinks or mesh enclosures.
Providing air through mesh-like barriers is a very different goal to airflow in a clean environment, so different fan types specialize in this area.
There isn’t a clear winner in 120mm vs 140mm for static pressure, so it will really come down to whatever your setup allows you to install (we recommend 140mm if possible due to its CFM advantage, but either is fine).
So if you want decent static pressure fans to cool your CPU heatsink (or a value bundle for mesh casing setups also), the Arctic P12 for 120mm, or P14 for 140mm are the ideal picks at a mid-range budget.
But if you’re interested in our other fan picks below, don’t fret; the choices on this guide all have decent static pressure ratings in comparison to many similar options, and this spec is not as important if you’re not dealing with heatsink/mesh coverage.
Best High-End 140mm Fan: Noctua NF-A14 iPPC-3000
If you’re after the best fan cooling possible, the NF-A14s are one of the best offerings to fit the bill.
With incredible high-quality material/blade designs and up to 3000 RPM mean the A14 have one of the best CFMs on the market.
It’s worth noting these things can get loud at the highest RPM (which you’ll only hear during intensive operation), but if you’re after the best airflow, they’re fit for the job.
The NF-A14s (and F-12s) also have excellent static pressure, and are a perfect choice if you’re looking for heatsink/mesh cooling.
Best High-End 120mm Fan: Noctua NF-F12 iPPC 3000
The smaller brother of the NF-A14 is a fantastic choice for setting up 120mm fan cooling.
Achieving similar top-range CFM and RPMs with their superb materials (relative to other 120mm fans) these products are one of the best PC case fans for gaming, overclocking, and other high-end usages.
120mm vs 140mm Fan Noise
Although the differences on the cooling/airflow front are notable, we think the real reason to prefer 140mm fans (if possible) is their quieter operation.
We’ll repeat the same disclaimer; this is on average. A low noise-focussed 120mm fan will be quieter than a standard 140mm offering (and would still be a decent solution for a quiet build).
But if we’re talking about how to achieve the quietest fan setup, we definitely prefer 140mm-focussed setups.
The reason is relatively straightforward; as per our airflow section, 120mm fans have to spin at slightly faster RPMs to achieve similar cooling to 140mm fans.
Now while other factors do matter in decibel production, if you put two similar fans head-to-head, the RPM they work at will be the largest indicator of which makes more noise.
You may think the blade fan size must matter too, but have you ever thought about how a ceiling fan in a house can be nearly inaudible, but a tiny desk fan can get loud very quickly? It’s primarily to do with the ceiling fan having to spin way less to cool its environment.
In other words; because 140mm fans have to spin less fast to achieve suitable thermal control, they produce notably less noise on average than 120mm fans.
This has been demonstrated in numerous benchmarks and tests.
If you’re looking at a quiet PC but only have 120mm fan availability in certain parts, don’t worry; the recommended quiet 120mm fan pick below still achieves very low DB(a) cooling.
PWM vs DC Fans
While not strictly related to the 120mm/140mm battle, if you’re interested in noise, it’s worth briefly touching on this spec as you’re bound to see it in comparing quiet fans.
DC (direct current) fans are controlled by 3-pin headers on your motherboard, while PWM (pulse width modulation) adds an additional pin that allows the motor and voltage requirements of the fan to signal each other more effectively than DC units.
Both types of fans require a minimum RPM to operate (too low and they begin to stall, act erratically, etc.) and due to the PWM’s improved signaling, fans with this functionality can achieve lower RPMs (either by the user’s control or automatically during less-intense operation).
So for something focussed on quiet operation, it’s a good little bonus to have a PWM fan (if your motherboard has 4-pin headers, which many modern ones do).
(Don’t fret too much about this though, you can connect a 3-pin fan to a 4-pin header and vice versa, you just won’t get PWM functionality from a 3-pin header or fan).
Though to be clear; a good DC fan still goes to fairly low RPMs that we expect will satisfy even those users focused on a silent build (providing they’re using a decent enough case).
Go for PWM fans if you have 4-pin headers by all means, but only consider this a nice-to-have, and not a super important factor of a quiet machine.
Best Quiet 140mm Fan: Be Quiet! BL040
Be Quiet!, as you might expect from the name, is one of the leading brands in silent PC cases, and their work in fans is just as impressive.
The BL040 is fantastic at keeping its great CFM/airflow to a very low-decibel standard; if used with a decent quiet computer case, you’ll have the best chance at a nearly silent PC setup.
Best Quiet 120mm Fan: Be Quiet! BL039
The BL40’s smaller brother is a fantastic product for 120mm fan builds too.
It outputs a slightly higher decibel rating per fan than the 140mm version, but this is a difference of only 0.4 Db(a) at maximum speed. The BL039 is still very quiet when compared to nearly every other 120mm fan on the market.
120mm vs 140mm Size / Compatability
Sometimes, comparing the differences between 120mm and 140mm PC fans is apples and oranges, because it really depends on the computer case’s compatibility.
The average 120mm fan dimensions are 120mm x 120mm x 25mm
The average 140mm fan dimensions are 140mm x 140mm x 25mm
In other words, although these can vary in thickness, 140mm are always notably larger, and most PC cases can accommodate fewer 140mm fans than 120mm ones.
We’ll reiterate one of our main points through the feature: it’s better to focus on getting a high-quality PC case for your needs. That could be anything from the best all-round, the largest, the cheapest, or the quietest, whether it accommodates 120mm setups or 140mm setups better is a secondary point.
But if you have the luxury of choosing between them, you will often be comparing larger amounts of 120mm fans and how they can perform versus less 140mm fans. The most common battle is 3 120mm vs 2 140mm.
3 120mm Fans vs 2 140mm Fans
For cooling, 3 120mm fans tend to have slightly better CFM /air output than 2 140mm fan builds.
But this isn’t the w