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Quietest 40mm fan: Sunon's HA40101V4 lists 15.7 dB(A) at one meter

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· 8 min read

Illustration of a small square 40mm cooling fan beside a 3D printer hotend and its heatsink

Among 40mm fans rated 1 m from the intake, Sunon's HA40101V4 lists the lowest figure, 15.7 dB(A) at 5000 RPM and 12 V, with Delta's AFB0412LA-A at 16.0 at 4000 RPM.

At 24 V on the same basis, Sunon's 40 x 20 mm MF40202V2 lists 21.0 dB(A) and SANYO DENKI's 40 x 10 mm 109P0424H901 lists 25.

Noctua names no distance: its NF-A4x20 PWM lists 14.9 dB(A) and its NF-A4x10 24V PWM 19.6, ranked only against other Noctua fans. Orion lists 20.1 dBA for its OD4010-24LB with no method. Every figure is for the fan at its full rated speed.

On this page
  1. How we chose
  2. Our picks
  3. How to choose
  4. Comparison
  5. FAQs
  6. Bottom line
  7. Review history

A quick look at the quietest 40mm fans

A 40mm fan is the small square fan that cools a 3D printer hotend, a router, a NAS board or a mini PC power stage. Even the slowest versions here turn at 4000 RPM or more at full speed, so the quietest 40mm fan is mostly a question of speed, frame depth and voltage.

We read the sheets from Sunon, Delta, SANYO DENKI, Noctua and Orion. Three of those makers measure 1 m from the fan intake, and they form the only list here that crosses brands.

Noctua and Orion print figures with no distance at all, so a Noctua number is compared only with other Noctua numbers, and the same goes for Orion. The picks below mix the two kinds, and each one says which it is.

How did we pick these 40mm fans?

Each 40mm fan on this page carries a decibel rating that its maker published for a US model number, and two figures share a list only when both makers state the same measuring distance.

We read Sunon's model search and specification PDFs, Delta's US product pages and specification PDFs, SANYO DENKI's product pages and its 2025 to 2026 San Ace catalog, Noctua's infosheets and specification pages, and Orion's series pages and datasheets, all on November 5, 2026. Distributor listings were used only to confirm that Sunon's part numbers are sold in the US, never for a figure.

Noctua's site returned "Too Many Requests" errors for its NF-A4x20 and NF-A4x10 5V pages, so we read the Internet Archive copies of Noctua's own pages, dated April to July 2026, and say so beside each figure.

Each figure is for a bare fan at full rated speed, which is not the same as a fan inside a printer shroud. None of the five makers prints a price, so no pick shows one. QuietSpecs did not put a microphone to any of these fans; the numbers are the makers' own, from the sources below.

QuietSpecs' picks of the quietest 40mm fans

Prices as of Nov 5. Product prices and availability are accurate as of the date/time indicated and are subject to change.

Lowest 1 m figure, 15.7 dB(A) at 12 V

Sunon HA40101V4 40x10mm 12V MagLev fan

  • Noise: 15.7 dB(A) at 1 m from the intake, 5000 RPM (Sunon sheet)
  • Price: No maker list price
  • Best for: 12 V routers, NAS boxes and enclosures where the fan runs all day
  • Skip it if: Your printer runs its fans at 24 V

Sunon's sheet for the HA40101V4-10000-A99 lists "ACOUSTIC NOISE 15.7 dB(A)" at 5000 RPM, taken in Sunon's semi-anechoic room 1 m from the intake. No fan rated on that shared Sunon, Delta and SANYO DENKI basis lists less.

It is a 40 x 10 mm, 12 V MagLev fan on Sunon's Vapo bearing, moving 5.4 CFM on 0.34 W, and it starts at 3.7 V. US distributors sell it as HA40101V4-1000U-A99.

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Slowest 1 m fan, 16.0 dB(A) at 4000 RPM

Delta AFB0412LA-A 40x10mm 12V fan

  • Noise: 16.0 dB(A) average, 19.5 maximum, at 1 m from the intake, 4000 RPM (Delta sheet)
  • Price: No maker list price
  • Best for: Low-heat electronics that need a ball bearing and a published worst case
  • Skip it if: You are cooling a hotend heatsink and need more air

Delta's specification for the AFB0412LA-A gives "16.0 (MAX. 19.5) dB-A" at 4000 RPM, measured in an anechoic chamber "AT A DISTANCE OF ONE METER FROM THE FAN INTAKE".

It sits 0.3 dB(A) above the Sunon on the same distance, and like Sunon's EF40201B3 sheet it prints a worst-case figure beside the average. It spins 1000 RPM slower than the Sunon, so it moves less air, 4.39 CFM.

Delta's US page marks it "Active", and the 5 V AFB0405LA-A lists the same 16.0.

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Lowest 24 V figure at 1 m, 21.0 dB(A)

Sunon MF40202V2 40x20mm 24V MagLev fan

  • Noise: 21.0 dB(A) at 1 m from the intake, 6000 RPM (Sunon sheet and search)
  • Price: No maker list price
  • Best for: 24 V printers and enclosures with room for a 20 mm fan
  • Skip it if: Your shroud only takes a 10 mm fan

Sunon lists the MF40202V2 at 21 dBA in its model search, and the linked sheet gives "21.0 dB(A)" at 6000 RPM and 24 VDC, measured 1 m from the intake. That is the lowest 24 V figure on the 1 m basis.

For a printer, depth decides it: the frame is 40 x 40 x 20 mm, so it fits only where the shroud takes a 20 mm fan. It moves 7.7 CFM on 0.60 W.

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24 V in a 10 mm frame, 25 dB(A) at 1 m

SANYO DENKI San Ace 40 109P0424H901 40x10mm 24V fan

  • Noise: 25 dB(A) at 1 m from the air inlet, 6200 RPM (SANYO DENKI page and catalog)
  • Price: No maker list price
  • Best for: Replacing a 24 V 4010 hotend fan with a datasheet-backed part
  • Skip it if: A 20 mm fan fits, where the Sunon MF40202V2 lists less

SANYO DENKI lists "SPL [dB(A)] 25" for the 109P0424H901 at 6200 RPM, and its San Ace catalog defines SPL as the level "at 1 m away from the air inlet".

It is the only 40 x 10 mm, 24 V fan we found with a figure on the 1 m basis, which makes it the closest match for a printer built around a 24 V, 10 mm fan.

It moves 5.3 CFM, has a pulse sensor, and runs from 20.4 to 27.6 V. The 12 V and 5 V versions list the same 25.

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Noctua's 24 V printer fan, 19.6 dB(A)

Noctua NF-A4x10 24V PWM

Noctua NF-A4x10 24V PWM
  • Noise: 19.6 dB(A) at 5000 RPM, no distance stated (Noctua infosheet)
  • Price: $15.95 at Amazon, checked Nov 5
  • Best for: Ender 3 and CR-10 style printers that use 2-pin JST XHP-2 fan sockets
  • Skip it if: You want a figure measured on a stated test distance

At 5000 RPM, Noctua's infosheet rates the NF-A4x10 24V PWM at "19.6 dB(A)" and names no measuring distance, so it is ranked only against other Noctua fans.

Noctua calls it "ideal for 24V-based 3D printers" and puts an NA-AC9 cable in the box for the 2-pin JST XHP-2 sockets on printers such as the Ender 3 and CR-10. A Low-Noise Adaptor is included too, but this sheet prints no figure for it.

It moves 8.9 m³/h and needs at least 17 V to start.

Check price at Amazon

Lowest Noctua 40mm figure, 14.9 dB(A)

Noctua NF-A4x20 PWM

Noctua NF-A4x20 PWM
  • Noise: 14.9 dB(A) at 5000 rpm, 12.2 dB(A) with LNA (4400 rpm), no distance stated (Noctua page)
  • Price: $15.95 at Amazon, checked Nov 5
  • Best for: 12 V boxes and printer electronics bays with room for a 20 mm fan
  • Skip it if: Your mount only takes 10 mm

At its 5000 rpm top speed, Noctua's specification page lists the NF-A4x20 PWM at "14.9 dB(A)", falling to 12.2 once the Low-Noise Adaptor caps it at 4400 rpm.

It is 20 mm deep, and the extra depth buys more air and pressure than the 10 mm NF-A4x10 at the same speed: 9.4 m³/h and 2.26 mm H₂O. Noctua names no measuring distance.

The FLX version adds an Ultra-Low-Noise Adaptor rated 8.5 dB(A) at 3700 rpm, and the 5V and 5V PWM versions also list 14.9.

Check price at Amazon

How to choose

New to the units? Read dBA explained or sones vs decibels.

Which 40mm fan is the quietest?

Sunon's HA40101V4 is the quietest 40mm fan on the 1 m basis, at 15.7 dB(A) and 5000 RPM, with Delta's AFB0412LA-A at 16.0 dB(A) and 4000 RPM a step behind.

These are the lowest 40mm figures we found measured 1 m from the intake, lowest first, at full rated speed:

  • Sunon HA40101V4, 40 x 10 mm, 12 V: 15.7 dB(A) at 5000 RPM
  • Delta AFB0412LA-A, 40 x 10 mm, 12 V: 16.0 dB(A) at 4000 RPM
  • Delta AFB0405LA-A, 40 x 10 mm, 5 V: 16.0 dB(A) at 4000 RPM
  • Sunon EF40201B3, 40 x 20 mm, 12 V: 16.2 dB(A) nominal at 5200 RPM
  • Sunon MF40201V3, 40 x 20 mm, 12 V: 16.5 dB(A) at 5000 RPM
  • Sunon MF40101V2, 40 x 10 mm, 12 V: 20.6 dB(A) at 5800 RPM
  • SANYO DENKI 109P0412M901, 40 x 10 mm, 12 V: 21 dB(A) at 5000 min-1
  • Sunon MF40202V2, 40 x 20 mm, 24 V: 21.0 dB(A) at 6000 RPM
  • Delta AFB0412MA-A, 40 x 10 mm, 12 V: 21.5 dB(A) at 5000 RPM
  • SANYO DENKI 109P0424H901, 40 x 10 mm, 24 V: 25 dB(A) at 6200 min-1

The top five sit within 0.8 dB(A) of each other. Sunon uses a semi-anechoic chamber and Delta an anechoic one, so a gap that small is closer to a tie than a ranking.

How do 40mm fan makers measure noise?

Sunon, Delta and SANYO DENKI measure 1 m from the intake, Noctua names no distance, and Orion prints no method at all on its 40mm datasheets.

The 1 m makers

Delta's sheet says noise is measured "IN FREE AIR IN ANECHOIC CHAMBER WITH B & K SOUND LEVEL METER WITH MICROPHONE AT A DISTANCE OF ONE METER FROM THE FAN INTAKE." Sunon's sheets use a semi-anechoic room "with background noise level below 15dB(A)" and the same 1 m.

SANYO DENKI's catalog defines its SPL column as "A-weighted sound pressure level (SPL) at 1 m away from the air inlet." That puts all three on a shared footing, as far as their documents go. Why the microphone distance decides whether two ratings can meet is set out in comparing decibel ratings.

Noctua and Orion

Noctua's infosheets print "Max. acoustical noise" beside a top speed, with and without the Low-Noise Adaptor, and say nothing about distance or room. The same is true of the 120mm and 140mm figures covered on our Noctua decibel page.

Orion's OD4010 and OD4020 datasheets give a "Noise Level (dBA)" column and nothing else. Its own web table also prints 36.3 dBA for the 5 V OD4010-05MB where the datasheet says 26.3, so we used the datasheet.

What is the quietest 24V 40mm fan for a 3D printer?

On the 1 m basis, Sunon's MF40202V2 is the quietest 24 V 40mm fan, at 21.0 dB(A) and 6000 RPM, but it is 20 mm deep; SANYO DENKI's 10 mm 109P0424H901 lists 25 dB(A).

Noctua builds its 24V NF-A4x10 for "24V-based 3D printers" and names Creality's Ender 3 and CR-10 and Anycubic's Mega as printers its cable fits. Check your own printer's fan voltage before ordering, since the 5 V and 12 V versions of these fans are separate parts.

Ranked by basis, these are the 24 V fans we found:

  • 1 m, Sunon MF40202V2, 40 x 20 mm: 21.0 dB(A) at 6000 RPM, 7.7 CFM
  • 1 m, SANYO DENKI 109P0424H901, 40 x 10 mm: 25 dB(A) at 6200 min-1, 5.3 CFM
  • 1 m, Sunon MF40202V1, 40 x 20 mm: 25.5 dB(A) at 7000 RPM, 8.9 CFM
  • No distance, Noctua NF-A4x10 24V PWM (40 x 10 mm): 19.6 dB(A), 5000 RPM
  • No distance, Orion OD4010-24LB, 40 x 10.5 mm: 20.1 dBA at 4000 RPM
  • No distance on its page, SANYO DENKI 9RA0424F6001, 40 x 20 mm: 21 dB(A) at 6500 min-1

Sunon's model search lists no 24 V fan in a 40 x 10 mm frame, and SANYO DENKI's 21 dB(A) 109P0412M901 has no 24 V version. That leaves the 109P0424H901 as the only 10 mm, 24 V fan with a 1 m figure. Our guide to the quietest 3D printers covers the noise of the machine as a whole.

The printer plug question

Noctua is the only maker here that ships a printer connector: its NA-AC9 cable fits "the 2-pin JST XHP-2 2.5mm sockets used on many popular 3D printer models". None of the Sunon, Delta, SANYO DENKI or Orion sheets we read mentions a printer connector, so expect to crimp or splice.

Is a 40x20 fan quieter than a 40x10 fan?

Usually, for similar airflow. Sunon's 20 mm MF40201V3 lists 16.5 dB(A) for 6.3 CFM, while its 10 mm MF40101V2 needs 20.6 dB(A) to move 7.0 CFM.

Noctua shows the same pattern at a matched 5000 RPM: 14.9 dB(A) and 9.4 m³/h for the 20 mm NF-A4x20 PWM, against 19.6 dB(A) and 8.9 m³/h for the 10 mm NF-A4x10 PWM.

The deeper frame lets the 20 mm Sunon move its air at 5000 RPM, where the 10 mm one turns at 5800. The cost is 10 mm of space, which many hotend shrouds and slim enclosures do not have.

What is the quietest 5V 40mm fan?

Delta's AFB0405LA-A is the quietest 5 V 40mm fan on the 1 m basis, at 16.0 dB(A) and 4000 RPM, followed by Sunon's 20 mm MF40200V3 at 16.5.

The 5 V versions in this group list exactly the same figures as their 12 V twins: Delta's LA-A pair at 16.0, Sunon's MF40100V2 at 20.6 and SANYO DENKI's 109P0405M901 at 21.

Among Noctua's own figures, the 20 mm NF-A4x20 5V and 5V PWM list 14.9 dB(A), and the 10 mm NF-A4x10 5V lists 17.9. The NF-A4x10 5V PWM lists 19.6 and comes with a USB cable that Noctua says lets it run on power banks.

Does a quiet 40mm fan move enough air?

Not always: the slowest fans here move the least air, and Delta's AFB0412LA-A gives 4.39 CFM against 7.0 for Sunon's louder MF40101V2.

Speed drives both numbers. Across Delta's 12 V 40 x 10 mm line the noise climbs from 16.0 dB(A) at 4000 RPM to 21.5 at 5000, 27.0 at 6000, 31.5 at 7000 and 35.5 at 8000.

None of these fan makers states how much airflow a hotend needs; that comes from the printer or hotend maker. Swapping a printer's stock fan for a slower one trades away cooling that the printer maker sized for.

Slowing a fan you already own

A low-noise adaptor or a PWM curve cuts noise by cutting speed. With its adaptor fitted, Noctua's 12 V NF-A4x10 PWM goes from 19.6 dB(A) to 12.9 and from 5000 RPM to 3700, while its airflow falls from 8.9 to 6.6 m³/h. Our page on making PC fans quieter covers the adaptor and curve settings in more depth.

Which 40mm fans could not be ranked?

Sunon's HA40201V4 could not be ranked, because its sheet contradicts itself on distance, and neither could Winsinn's or GDSTime's 40mm fans, which have no maker figure tied to a model number.

The HA40201V4 sheet prints "12.3 dB(A) @1M" at 4500 RPM, then draws the test with the microphone at "0.1 METER" from the intake. It also says the chamber's background noise sits "below 15dB(A)", above the figure itself. We quote 12.3 and leave it out of the 1 m list.

Winsinn's own site lists dBA figures for its 40mm fans by frame size and voltage, but gives no model numbers to tie them to a product sold in the US, so we left them out. GDSTime's site lists 40mm models such as the GDB4010 blower without a noise figure that we could find.

SANYO DENKI's 9RA fans, including the 24 V 9RA0424F6001 at 21 dB(A), have pages but are not in the 2025 to 2026 catalog we searched, and the pages name no distance. We rank them only among SANYO DENKI's own figures.

How the quietest 40mm fans compare

ProductNoiseSizeVoltageAirflowPrice
Sunon HA40101V4-10000-A99 (sold by US distributors as HA40101V4-1000U-A99)15.7 dB(A) at 1 m from the intake, 5000 RPM (Sunon sheet)40 x 40 x 10 mm12 VDC rated, 3.7 to 13.8 VDC range5.4 CFM, 0.09 inch H2ONot verified yet
Delta AFB0412LA-A16.0 dB(A) average, 19.5 maximum, at 1 m from the intake, 4000 RPM (Delta sheet)40 x 40 x 10 mm12 VDC rated, 9.0 to 13.8 VDC range4.394 CFM, 1.737 mmH2ONot verified yet
Sunon MF40202V2-10000-A9921.0 dB(A) at 1 m from the intake, 6000 RPM (Sunon sheet and search)40 x 40 x 20 mm24 VDC rated, 8 to 27.6 VDC range7.7 CFM, 0.17 inch H2ONot verified yet
SANYO DENKI 109P0424H90125 dB(A) at 1 m from the air inlet, 6200 RPM (SANYO DENKI page and catalog)40 x 40 x 10 mm24 V rated, 20.4 to 27.6 V range5.3 CFM, 41.2 PaNot verified yet
Noctua NF-A4x10 24V PWM19.6 dB(A) at 5000 RPM, no distance stated (Noctua infosheet)40 x 40 x 10 mm24 V, starts at 17 V or above8.9 m³/h, 1.95 mmH2O$15.95
Noctua NF-A4x20 PWM14.9 dB(A) at 5000 rpm, 12.2 dB(A) with LNA (4400 rpm), no distance stated (Noctua page)40 x 40 x 20 mm12 V, starts at 8 V9.4 m³/h (5.53 CFM), 2.26 mm H₂O$15.95

Prices as of Nov 5. Product prices and availability are accurate as of the date/time indicated and are subject to change.

Frequently asked questions

What is the quietest 40mm fan?

On the 1 m from the intake basis that Sunon, Delta and SANYO DENKI share, Sunon's HA40101V4 at 15.7 dB(A), then Delta's AFB0412LA-A at 16.0. Noctua's NF-A4x20 PWM lists 14.9 dB(A) but gives no distance, so it is compared only with other Noctua fans.

What is the quietest 24V 40mm fan for a 3D printer?

On the 1 m basis, Sunon's 40 x 20 mm MF40202V2 at 21.0 dB(A). For a 10 mm frame, SANYO DENKI's 109P0424H901 lists 25 dB(A) at 1 m. Noctua's NF-A4x10 24V PWM lists 19.6 dB(A) with no distance and ships with a printer cable.

Can I run a 12V 40mm fan on a 24V printer?

Not directly. The 12 V sheets here cap the supply at 13.2 to 13.8 V, and Noctua warns that its 5V PWM model "will be damaged" on 12 V sources. Buy the fan in your printer's voltage.

Is a 40x20 fan quieter than a 40x10?

Often, for similar airflow. Sunon's 20 mm MF40201V3 lists 16.5 dB(A) for 6.3 CFM, while its 10 mm MF40101V2 needs 20.6 dB(A) for 7.0 CFM. Noctua's 20 mm NF-A4x20 lists 14.9 against 19.6 for the 10 mm PWM model at 5000 RPM.

Why do Noctua's 40mm figures not rank against Sunon or Delta?

Noctua prints a "Max. acoustical noise" figure without saying where the microphone was. Sunon and Delta put it 1 m from the intake and SANYO DENKI 1 m from the air inlet, so only those three share a basis.

Does a low-noise adaptor help on a 40mm fan?

On Noctua's numbers, yes. The 12 V NF-A4x10 PWM falls to 12.9 dB(A) from 19.6 when its adaptor slows it to 3700 RPM, and the NF-A4x20 PWM from 14.9 to 12.2. Each also loses airflow, which matters on a hotend.

The bottom line

I expected Noctua to run away with this one, the way it does in most fan lists. On its own sheets it does post the lowest 40mm number, 14.9 dB(A), but Noctua never says where the microphone stood. Sunon, Delta and SANYO DENKI all say 1 m from the intake, and among those, Sunon's HA40101V4 and Delta's AFB0412LA-A sit 0.3 dB(A) apart near 16. That small gap tells me those two are level, not that one beats the other.

For a 24 V printer, I would look at the MF40202V2 first if the shroud takes a 20 mm fan, and at Noctua's 24V NF-A4x10 if it only takes 10 mm and I wanted the printer plug in the box. I would also check airflow before buying the slowest fan on this page, since a hotend heatsink needs air more than it needs silence.

Stanley Alu, founder and editor

What we also considered

These are worth knowing about, and why they didn't make the list.

  • Sunon MF40201V3 40x20mm 12V MagLev fan

    A 40 x 20 mm, 12 V Sunon that lists 16.5 dB(A) at 5000 RPM and 1 m, with 6.3 CFM. Its 5 V twin, the MF40200V3, lists the same.

    Search Amazon for this model

  • Delta AFB0405LA-A 40x10mm 5V fan

    The 5 V twin of the AFB0412LA-A, with the same 16.0 dB(A) at 4000 RPM and the same one meter test.

    Search Amazon for this model

  • Sunon MF40101V2 40x10mm 12V MagLev fan

    Sunon's mid-speed 40 x 10 mm MagLev fan, 20.6 dB(A) at 5800 RPM and 1 m, with 7.0 CFM; the 5 V MF40100V2 matches it.

    Search Amazon for this model

  • SANYO DENKI San Ace 40 109P0412M901 40x10mm 12V fan

    SANYO DENKI's slower 40 x 10 mm fan lists 21 dB(A) at 5000 min-1 and 1 m, but only at 12 V and 5 V.

    Search Amazon for this model

  • Delta AFB0412MA-A 40x10mm 12V fan

    Delta's 5000 RPM step up from the AFB0412LA-A, at 21.5 dB(A) and 1 m, with 5.67 CFM.

    Search Amazon for this model

  • Sunon HA40201V4 40x20mm 12V MagLev fan

    Sunon lists 12.3 dB(A) "@1M" at 4500 RPM, but the same sheet's test section puts the microphone 0.1 m away, so the figure is quoted and not ranked.

    Search Amazon for this model

  • Noctua NF-A4x10 FLX

    A 3-pin 12 V NF-A4x10 at 17.9 dB(A) and 4500 RPM, or 12.9 with its adaptor; no distance is given.

    See it at Amazon

  • Noctua NF-A4x10 5V PWM

    The 5 V PWM NF-A4x10 with a USB cable in the box, 19.6 dB(A) at 5000 RPM and no distance given.

    See it at Amazon

  • SANYO DENKI San Ace 40 9RA0424F6001 40x20mm 24V fan

    A 40 x 20 mm, 24 V San Ace at 21 dB(A) and 6500 min-1, but its page names no distance and the 9RA 40mm models are missing from the catalog we searched.

    Search Amazon for this model

  • Orion OD4010-24LB 40mm 24V fan

    Orion lists 20.1 dBA at 4000 RPM for the 24 V OD4010-24LB, with no test distance or method on the datasheet.

    See it at Amazon

How we reviewed this article

Every statement here comes from the 23 maker documents, standards and agency pages listed under Sources, quoted where the wording matters. We did not measure, inspect or repair anything ourselves. Each substantive revision is dated below. How we work

  1. Current version

    First published, written by Stanley Alu.

Sources

Every figure on this page was read on one of the pages below. We did not measure anything ourselves.

All 23 sources
Manufacturer pages and manuals for every product

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