I have a clip-on guitar tuner. It is set to 440 cps. I want to tune down a half from E to Eb. What cps do I need to change it to? P.S. I don't know what a cent is.

  • If your tuner only supports standard guitar strings (E, A, D, G, B), and you are able to tune a string by ear while listening to the same note, then another alternative is to proceed by tuning from the fifth string (A) while playing Ab on the sixth, then proceed accordingly for the other strings, and finally tune the sixth based on the first. Commented Jun 10 at 17:27
  • Why not running while getting the first fret?
    – Tom
    Commented Jun 11 at 13:05

2 Answers 2


Tuning down a half step is a pretty common thing. You have a few possible options for doing that. Changing the frequency is not enough of an adjustment to tune down one note.

First things first, check the manual for your tuner if you have it. Some clip on tuners have a setting allowing you to set it to tune a half step down automatically then tune the way you normally do, E,A,D,G,B,E. The result is Eb,Ab,Db,Gb,Bb,Eb.

If you do not have this option then you can manually tune down a half step by selecting different notes as long as your tuner is chromatic, meaning it can tune to any of the 12 notes. You will be using sharps instead of flats because tuners only use natural and sharp notes. You will tune to D#,G#,C#,F#,A#,D# and end up with the same result.

Also FYI, a cent is 1/100th of the distance between notes, so if you go up 100 cents from E you will get to the next note, F.


In equal temperament, each half step represents a factor of the twelfth root of two (2 ^ (1/12)) in frequency. If A is 440 Hz, therefore, then (in equal temperament) A♭/G♯ will be approximately 415.30 Hz.

You may find that the frequency you want is slightly different if you are not setting the pitch level yourself (that is, if you are working with other instruments or a recording and have to tune your instrument to match). This could be a result of

  • starting with a frequency for A other than 440 Hz
  • a difference between the recording speed and the playback speed
  • using a temperament other than equal.

If this is the case, tune your instrument to the recording or the other instruments rather than using a tuner. There is usually no need to put a number on the frequency you're tuning to.

(The factor for a cent is the hundredth root of the factor for a half step; equivalently, it is the 1200th root of two, because a half step is 100 cents. But you don't need to know what a cent is to be able to tune down a half step.)

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