Free Online Ukulele Tuner
Plug in your microphone, pluck a string, and tune by ear or against the live cents meter. Standard re-entrant GCEA, Low-G, and Baritone DGBE all supported.
Reference Tones
Tap a string to hear it. Tune by ear against the reference if you don't want to enable the microphone.
🐶 "My dog has fleas"
The four open strings of a standard re-entrant ukulele — G, C, E, A — spell out the melody of the phrase "my dog has fleas." Hum the tune and you're hearing the tuning. If you can sing it, you can tune your ukulele by ear against the reference tones above.
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How to use this tuner
1. Pick your tuning above. Standard re-entrant GCEA covers soprano, concert and tenor ukuleles — about 90% of instruments in the wild. Low-G is mostly tenor. Baritone is its own thing — physically larger, with the deeper DGBE tuning.
2. Click "Enable Microphone." Your browser will ask for permission. Audio is processed locally in your browser using the Web Audio API and never leaves your device.
3. Pluck one string. The big display shows the detected note (e.g., "A4"), the actual frequency in Hz, and the cents-offset from the target. The needle on the meter shows how far sharp or flat you are. Green is within ±5 cents (in tune); yellow is within ±15 cents (close); red is more than 30 cents off.
4. Adjust the tuning peg. The display shows "tune UP" or "tune DOWN." Ukulele strings respond quickly — a small turn moves the pitch a lot. Pluck again, check the meter, repeat. The display freezes at the last detected reading after the string decays, so you can look up from the instrument and read what you played without rushing.
5. Repeat for all four strings. The tuner auto-detects which string you're playing by matching to the nearest target pitch. If it keeps jumping between strings (common between the re-entrant G4 and the high A4 because they're close in pitch), lock the target string manually with the buttons.
Why a new ukulele goes out of tune so fast
If you just bought your first ukulele, it will go out of tune every few minutes for the first day or two. This is completely normal and is not a problem with the instrument. Ukulele strings are nylon or fluorocarbon — soft synthetic polymers — and they stretch substantially under tension when first installed. Each time you tune up, the string accepts the new pitch but then continues to stretch by a small fraction of a percent for the next few hours, lowering the pitch again.
The string is settling. After about a week of normal playing — and constant retuning — the stretching equilibriates and the strings will hold tune for hours at a time. You can accelerate the process by gently pulling each string away from the fretboard a few millimetres after tuning, which mechanically pre-stretches the polymer. Some players do this once or twice an hour during the first day.
The other variable is the tuning pegs. Inexpensive ukuleles ship with friction pegs — wooden pegs held in place purely by friction in the headstock. They work, but they slip easily under string tension. Geared tuners (the metal-and-plastic ones you'll find on guitars and on better ukuleles) are mechanically much more stable. Upgrading to geared tuners is the single most cost-effective improvement on a budget ukulele.
Ukulele tuning reference table
| Tuning | Strings (4 → 1) | Frequencies (Hz) | Used for |
|---|---|---|---|
| Standard (re-entrant) | G4 · C4 · E4 · A4 | 392.00 · 261.63 · 329.63 · 440.00 | Soprano, concert, tenor |
| Low-G | G3 · C4 · E4 · A4 | 196.00 · 261.63 · 329.63 · 440.00 | Tenor (mostly), fingerstyle |
| Baritone | D3 · G3 · B3 · E4 | 146.83 · 196.00 · 246.94 · 329.63 | Baritone only |
| D tuning (historical) | A4 · D4 · F#4 · B4 | 440.00 · 293.66 · 369.99 · 493.88 | Old Hawaiian standard, pre-1930s |
| Slack-key (D6) | A4 · D4 · F#4 · B4 | 440.00 · 293.66 · 369.99 · 493.88 | Hawaiian slack-key, less common |
| Bass ukulele (U-Bass) | E1 · A1 · D2 · G2 | 41.20 · 55.00 · 73.42 · 98.00 | Acoustic bass ukulele only |
Highlighted row is the modern standard. The D tuning was the original Hawaiian ukulele tuning into the 1930s — a whole step higher than today's GCEA. Old sheet music and song books from before 1930 often assume D tuning, which is one reason some old ukulele chord shapes don't sound right on a modern instrument.
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A=440 and the cents you're chasing
The reference pitch this tuner uses is the international standard A4 = 440 Hz, codified by the International Organization for Standardization in 1955 (ISO 16:1975). All the other notes on the ukulele follow from this by the 12-tone equal temperament formula: each semitone is a frequency ratio of the 12th root of 2 (about 1.05946), so adjacent notes are about 5.95% apart in frequency.
A cent is 1/100th of a semitone — a very small interval. Most listeners can't distinguish less than about 5 cents on a sustained note, so the tuner's green zone (±5¢) is "good enough" for any practical playing. Within ±15 cents is still close enough that the chord will sound coherent. Beyond ±30 cents the note is audibly out of tune to almost anyone.
Orchestras sometimes use A=442 or A=443 — slightly sharper than the international standard — because higher tuning produces a brighter, more "alive" sound on bowed strings. This doesn't apply to ukulele tuning; A=440 is universal in the ukulele world. If you ever play with another instrument, tune both to 440 and you're matched.
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Sources & technical notes
- Jim Tranquada and John King, The 'Ukulele: A History (University of Hawai'i Press, 2012) — the standard scholarly history covering the 1879 Ravenscrag arrival, the D tuning era, and the transition to standard GCEA in the 1930s.
- International Organization for Standardization, ISO 16:1975 — Acoustics — Standard tuning frequency — the international standard for A4 = 440 Hz.
- The pitch detector uses the YIN method described in Alain de Cheveigné and Hideki Kawahara, "YIN, a fundamental frequency estimator for speech and music", Journal of the Acoustical Society of America 111(4), 2002.
- Parabolic interpolation around the detected period follows the method described in Mark Wirt, The Scientist and Engineer's Guide to Digital Signal Processing (California Technical Publishing, 1997).
- Standard ukulele string frequencies and the "my dog has fleas" mnemonic are documented in the Hawaiian Music Foundation's pedagogical materials and in Roy Sakuma's instructional books from the 1970s onward.
GCEA. My dog has fleas. Four strings, two and a half pounds, the cheerful little instrument that took over American sheet music in 1915 and again in 2006. Tune it up.