Why does my guitar keep going out of tune?
Always arrive at the note from below
If you overshoot and come back down, the tuning post keeps a small amount of slack that works itself out during the first few minutes of playing. Tune up to the note and stop there. If you overshoot, go below and come back up.
Why your tuner says in tune while chords sound wrong
Because tuners measure equal temperament, where every semitone is mathematically identical. That system is a deliberate compromise: it makes every key usable at the cost of no interval being acoustically perfect.
On guitar this shows up as chords that beat slightly even when every string reads green. It is not your tuner being wrong; it is the tuning system being a trade-off that has been standard for centuries.
What a cent is, and how precise you need to be
A cent is a hundredth of a semitone. Tuners use it because it is proportional — an octave is 1200 cents regardless of register, so the same value means the same perceived error high or low.
Trained listeners detect around 5–10 cents on sustained notes. Within ±5 cents is comfortably in tune for most instruments, and chasing beyond that is chasing the temperament compromise rather than a tuning error.
440 Hz and the 432 Hz claims
A4 = 440 Hz is the international reference pitch. Some orchestras tune slightly higher for brightness. The 432 Hz figure circulates online with claims about natural resonance and healing — there is no scientific support for those claims. If you enjoy how it sounds, that is a legitimate reason; the physics one is not.
