1. Check your tuning
Soprano, concert, and most tenor ukuleles normally use Standard GCEA. A Low-G setup uses the same note names but the G string sounds one octave lower. Baritone ukuleles normally use DGBE.
2. Tune one string at a time
Choose guided mode, select the string, and pluck it once. Let it ring while the tuner listens. Mute the other strings with your hand so they do not vibrate.
3. Turn the correct tuning peg slowly
If the tuner says the note is low, tighten the string in small movements. If it is high, loosen it. When loosening, go slightly below the target and tune upward again so the string settles more reliably.
4. Look for the green center
The string is ready when the pointer remains near the center and the tuner says “In tune.” Standard GCEA uses a ten-cent green range; the alternate tunings use eight cents.
5. Check all four strings again
Changing one string slightly changes tension across the instrument. After tuning A, return to G and make one final pass through all four strings.
Tuning a ukulele by microphone or by ear
A microphone tuner is the easiest starting point because it identifies the note and measures how far it is from the target. Choose Standard GCEA, allow microphone access, and play one open string at a time. A stable reading matters more than the first number that flashes on screen, because the beginning of a plucked note contains strong overtones. Wait a moment for the pitch to settle before moving a tuning peg.
Reference tones are useful when microphone access is unavailable and when you want to train your ear. Play the target tone, stop it, then pluck the matching string. Listen for a pulsing or wavering sound between the two pitches. That pulse slows as the string approaches the target. Keep the device volume moderate so its speaker does not overpower the ukulele or feed back into the microphone.
Understand flat, sharp and cents
A flat string is below its target pitch and normally needs a small increase in tension. A sharp string is above the target and needs to be loosened. The cents value shows the distance between the detected pitch and the exact note: 100 cents equals one semitone. You do not need to reach an unchanging zero, because every plucked string naturally moves a little as it decays.
Aim for a steady reading near the center. If a string is sharp, loosen it slightly below the target and then tune upward again. Approaching from below helps remove slack around the tuning post and makes the final pitch more stable. Never force a peg when the string feels unusually tight; first confirm the selected tuning, string and octave.
Tune safely after changing strings
New strings stretch during their first several playing sessions. Install and tune one string at a time when possible so the bridge and neck retain balanced tension. Bring each new string toward pitch gradually, checking that it sits correctly in the bridge, nut slot and tuning post. A string may need many small retunes before it settles, and that behavior is normal.
Confirm that the string set matches the instrument. Most soprano, concert and tenor ukuleles use High-G GCEA, while Low-G sets use a dedicated lower fourth string and baritone instruments normally use DGBE. If the pitch is far away from the expected octave or the tension feels unsafe, stop and check the package or a qualified repair technician rather than continuing to tighten.
Why a ukulele goes out of tune
Temperature, humidity, transport and playing pressure all change string tension. A warm instrument may read differently after moving into a cool room, and a newly installed set continues to stretch even when the pegs are working correctly. Tune before each practice, after moving between environments, and whenever familiar chords begin to sound sour.
Persistent instability can also come from loose tuning hardware, a string slipping around the post, binding at the nut or an old damaged string. Mark the peg position mentally and watch whether it moves. If one string repeatedly drops while the others stay stable, inspect that string and peg first. A tuner measures the symptom; it cannot repair a mechanical problem.