Why your guitar goes out of tune — the physics and the fixes
You tuned five minutes ago and the E string is already flat. It is not your ears and (usually) not your tuners — it is physics. Knowing the causes tells you exactly what to fix.
The usual suspects
- New strings stretch. Fresh strings creep for a day or two. Pre-stretch them: fret at the 12th, pull gently, retune, repeat.
- Temperature and humidity. Strings and wood expand and contract at different rates. A guitar carried from a cold car into a warm room can drift 10–20 cents. Let it acclimatise, then tune.
- Peg winding. Fewer, neater wraps (2–3) hold better than a bird's nest. The string should leave the post without kinks.
- The nut pinches. If a string pings while tuning, it is sticking in the nut slot and will release mid-song. A touch of graphite from a pencil in the slot works wonders.
- Aggressive playing. Big bends and heavy strumming pull strings sharp temporarily and flat permanently. Nothing is broken; just re-check more often.
Tune in a way that lasts
Always approach the note from below: if a string is sharp, drop it clearly below the target and come back up so the last peg movement tightens. Check the tuner after finishing all strings — total tension shifts the neck slightly, so the first string you tuned may have moved. This applies to every fretted instrument, from drop D guitar to ukulele, whose nylon strings stretch even longer than steel.
A 60-second pre-practice routine
- Open the tuner — the microphone starts listening immediately.
- Tune all strings, then re-check the first one.
- Stretch any string that keeps drifting.
- Set the metronome and start your session in tune and in time.
Calibration note: our tuner lets you shift the reference A4 from 440 Hz (415 for baroque ensembles, 442 for some orchestras) — but unless you play with others who use a different standard, leave it at 440.