Instrument Tuner
A chromatic tuner for any instrument — note, frequency and cents.
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not listening
How this test works
The tuner listens for a single sustained note and finds its fundamental frequency by autocorrelation — matching the waveform against a delayed copy of itself to find the period it repeats at. That approach is used rather than a frequency transform because a transform at a usable window length has bins tens of cents wide, which is far too coarse to tune with, and because it reports the wrong note whenever a harmonic is louder than the fundamental. The frequency is then converted to the nearest note in equal temperament at A = 440 Hz, with the difference shown in cents.
What the results mean
- Note and octave
- The nearest equal-tempered note, with its octave number. A4 is the A above middle C, at 440 Hz.
- Cents
- Hundredths of a semitone from that note. Negative is flat, positive is sharp, and ±5 is the usual in-tune window.
- Detected against target
- The frequency heard next to the frequency the note should be, so the size of the error is visible in hertz as well as cents.
- Clarity
- How strongly periodic the sound is. Below about half, the tool is looking at noise rather than a note and holds its last reading instead.
Common problems and fixes
- Nothing registers for a very low note
- Detection starts around 60 Hz. Below that — the bottom of a bass or an organ pedal — there is not enough of a period in the analysis window to be sure of.
- A wind instrument reads sharp as I warm up
- That is real, not a fault. Pitch rises with the temperature of the air column, which is why orchestras tune after warming up rather than before.
- Two notes at once give nonsense
- The detector finds one fundamental. For an interval or a chord, tune each note separately.
- My instrument is tuned to 442
- This is fixed at A = 440. An instrument at 442 will read consistently about 8 cents sharp — which is itself a usable way to work, once you know the offset.
Frequently asked questions
What is a cent in tuning?
A hundredth of a semitone, so 1,200 cents make an octave. It exists because pitch is perceived as a ratio rather than a difference: 3 Hz is enormous at the bottom of a bass and inaudible at the top of a violin, while 10 cents sounds the same amount out of tune everywhere.
Why does my tuner disagree with my piano?
Two likely reasons. Pianos are tuned with stretched octaves — the top notes deliberately sharp and the bottom flat — because of the physics of real strings, so a chromatic tuner reading equal temperament will disagree at both ends and both are correct. And the piano may simply be tuned to a different reference pitch.
Can I tune a ukulele or a violin with this?
Yes. It is chromatic, so it reports whatever note it hears rather than expecting a particular instrument — anything with a sustained note between roughly 60 and 1,500 Hz.