Tuning Theory
Understanding Pitch, Hertz, and Cents
Learn what Hz and cents mean, why A4 is usually 440Hz, and how tuners measure tiny pitch differences.
What pitch means
Pitch is how high or low a note sounds. Physically, it comes from vibration speed. A string that vibrates faster creates a higher pitch, while a slower vibration creates a lower pitch.
A tuner estimates that vibration rate and maps it to the nearest musical note. That is why clean, steady notes are easier to tune than noisy or short sounds.
Hertz measures vibration speed
Hertz, abbreviated Hz, means cycles per second. If a note is 440Hz, the vibration repeats 440 times every second. Standard concert pitch usually defines A4 as 440Hz, and the rest of the notes are calculated around it.
TrueTuner lets you change reference pitch because some ensembles use a slightly different standard, such as 442Hz. For most players, 440Hz is the right default.
Cents measure tuning distance
A semitone is divided into 100 cents. If the tuner says -12 cents, the note is twelve cents flat. If it says +8 cents, the note is eight cents sharp.
Cents are useful because they describe musical distance rather than raw frequency. The same Hz difference feels different in low and high registers, but cents stay musically consistent.
Why readings move
Real instruments are not perfectly static. A plucked string starts slightly sharp, then settles as the vibration decays. Finger pressure, pick attack, string age, and room noise can all move the reading.
Read the average center of the motion instead of reacting to every tiny flicker. A stable musical result matters more than a perfectly frozen number.