I just purchased a new 440 Hz tuning fork. But several different computer, iPad and iPhone tuners say it's almost half a percent sharp (around 442) of Concert A.

Is there any way to adjust the frequency of a tuning fork?

  • 1
    Are you sure it's a 440 fork? It is not uncommon to find one pitched at 442. And I'm curious what others have to say, but I don't think it's possible to tune a tuning fork. May 23, 2012 at 6:29
  • 1
    The package said 440, which is what I wanted. I wonder if someone put a fork for a European tuning or something in the wrong box?
    – hotpaw2
    May 23, 2012 at 6:47
  • 1
    personally, computer/mobile/tablets tuners have never accurate for me. have you try on the actual tuner?
    – Sufendy
    May 23, 2012 at 8:52
  • 1
    What iPhone tuner app did you use?
    – iddober
    May 23, 2012 at 11:26
  • 8
    There should be a frequency marked on the tuning fork itself. Trust that, not the box.
    – slim
    Nov 17, 2012 at 14:59

10 Answers 10


OK. I found a quick-and-dirty temporary solution.

As an online education forum suggested, a interesting school science experiment might be to see if adding weights and changing their position on a tuning fork will change the frequency of the fork. So I played science student, and tried the experiment.

Two big rubber bands on the tines clearly lowered the frequency... by way too much. Next I tried a couple strips of masking tape wrapped around the very end of the each tuning fork tine. That also lowered the frequency, by only a bit too much, to 20 cents flat. So I removed those pieces of tape and carefully measured them. Then I cut some tape strips about 9/29ths as long (actually a few mm longer). Wrapped the new lengths of tape on the fork tines, and the fork rang 3 cents flat. A little more fine trimming of the length of the tape with some sharp scissors, and I got the fork to measure within +-1 cent of 440 Hz, as measured against several calibrated iPhone tuners (both dial and strobe). The fork also now sounds good when played simultaneously with an mp3 of a 440 Hz tone to check for beats.

The tone probably isn't as pure, and tape will eventually age and wear, but this quick fix should work well enough until my next trip to a good music store for a better quality tuning fork.


You could tune it up if you have precision tools that can grind off just the right amount of metal from each tine (this would increase the frequency; to decrease the frequency you would need to add metal!) - but practically speaking that means no, you can't do it.

Does it look damaged? If not it is probably supposed to be a 442 tuning fork. If you need a 440 you'll need to just buy one.

Update based on the comment that you had bought a 440 fork:

Take it back to the shop, get them to check it. If their check shows it is a 442 then they can replace it. If they show it to be a 440 then maybe your tuners are out.

  • OP's comment from about a minute after you posted your answer: "The package said 440, which is what I wanted." May 23, 2012 at 13:31

It is defective. Return it for a refund. There is no practical way to recalibrate it. The reason people purchase a tuning fork in the first place is to get something that is exactly calibrated already.


Interesting question! No-one's mentioned temperature, so far. I'm off to put one in the freezer and another in the oven! I'll report back!

Just got back from hospital with frostbite on one hand and burns to the other... but surprisingly the tuning fork stayed in pitch! My theory stemmed from the British Yard which lives in London. It is exactly a yard long at a given temperature. Longer tuning fork = lower note, shorter = higher, surely?

  • LOL :D Did it damage the forks or alter the pitch?
    – Luke_0
    Nov 17, 2012 at 21:15
  • Changing the temperature of the fork also changes its elasticity, I expect, which would change its pitch, too. The colder the stiffer, raising the frequency. Perhaps this counteracts the change in length. Or, perhaps more likely, the effects of both changes are imperceptible.
    – phoog
    Apr 29, 2023 at 14:07
  • @phoog - colder would also make the tines shorter, thus raising the frequency. So, shorter rather than stiffer? Why the dv?
    – Tim
    Apr 29, 2023 at 15:03

As someone else stated, grinding off material from the end of the tines will increase the pitch.

However, grinding material off at the base bend of the fork will lower the pitch: there the material contributes much more to the fork's stiffness than to its inertia.

But it may well affect the purity of tone.


I had a cheap allegedly A440 fork that showed sharp on all tuners, and for reference, a better-quality fork showed exactly A. By filing a small amount from the outside of each tine near the join, and checking several times, it is now quite exact.

  • Did the forks disagree when you sounded then simultaneously?
    – phoog
    Sep 26, 2020 at 19:47

Just adjusted two A tuning forks I had to A#/Bb for my trumpet. Just got my guitar chromatic tuning meter and used my bench grinder to take equal amounts off the tines' ends a bit at a time until the frequency was right.

It's not rocket science or even heavy engineering. Just do it a bit at a time. It wasn't touchy either, it's not critically minute amounts taking off, just don't go daft. I was easy to keep both tines the same length by eye and the sustain on both seems the same as it was before. It's certainly not changed it noticeably. For the final tuning, I did let it cool down between grinds and checks just in case the temperature had a significant effect.

Regarding how accurate are digital tuners, they are based on quartz crystal oscillators that usually are easily accurate to 50 parts per million so, essentially, they are very accurate. Can't guarantee the same for the apps on phones though as they are often software solutions based on general phones so it depends on how the software has been written.


CHeap Chinese tuning forks (as of 2023) advertised as 440Hz are simply not that. DO NOT BUY. I have bought 4 from various sources, they produced sounds ranging from G to Bb. One was modifiable, by filing it down, the others - I sent back.


A bit of solder at the tip would lower the frequency. But to get both tines exactly right, that's tricky to do.

  • 1
    This is rather impracticable. First, few people have the resources to solder. Second, just getting that little bit soldered would cost way more than it's worth, and third, filing it down to the right amount would take forever. If you look at hotpaw2's answer, you can see how little needs to be added.
    – Luke_0
    Jun 2, 2012 at 0:36
  • Memories of tuning a Wurlitzer electric piano! I had a soldering iron. and filing it down didn't really take long. Solder's soft.
    – Laurence
    Jul 23, 2020 at 14:00

You can slowly grind it down to 440. Just make sure to cool it down each time before you check it. Aside from that 442 is MUCH better than 440 IMHO. I've been tuning all of instruments to 442 for the last couple years and have noticed a drastic improvement on not only my playing but also my health. Kid you not! Most of the really good musicians tune down half a step anyway, which is, surpise... 442! I know this is an old thread and all but I actually have a 440 tuning fork I would totally trade you. I don't really use tuning forks but I may grind it down anyway as the 440 bugs me something fierce.

  • 2
    Grinding it down would increase the frequency. Apr 28, 2023 at 4:20
  • 2
    Moreover, 442 is nowhere near half step down. It's a very slightly higher pitch than 440. Apr 28, 2023 at 18:58
  • 2
    @user1079505 442 isn't down at all! I realize your comment acknowledges this but it deserves to be called out more prominently. Most period-instrument baroque music is performed at A=415 Hz, a standard that was chosen because it is a half step down. 442 is around 1/13 of a half step above 440, 7.85 cents.
    – phoog
    Apr 29, 2023 at 14:16

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