Free Online Mandolin Tuner
Standard GDAE plus three scordaturas. 8 strings in 4 doubled courses — the tuner reads each course and locks the reading to the stable body of the pluck. Same pitches as a violin.
Reference Tones
Tap a course to hear it — each one plays as a pair of slightly-detuned strings for the natural mandolin chorus.
🎶 Tune BOTH strings of each course
Each course is two strings tuned to the same nominal pitch. Both must match each other to within a couple of cents — beyond that you get beating instead of the smooth mandolin chorus. The tuner reads whichever string is louder at the moment, so check each course twice: pluck the top string of the pair alone (mute the bottom), then the bottom alone, and adjust both to the same target.
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How to use this tuner
1. Pick your tuning. Standard GDAE for classical, bluegrass, Irish trad, jazz — almost everything. The other three (Cross A, Open D, Cajun A) are old-time scordaturas tied to specific tune repertoires.
2. Enable the microphone. Audio is processed locally; nothing is uploaded.
3. Tune the A course first. Pluck both strings of the A course together. The tuner shows the detected note (e.g., "A4"), the actual frequency, and cents-offset. Aim for green ±5 cents.
4. Match the two strings of each course separately. Pluck just the upper string of the course (with a finger muting the lower) — adjust to in tune. Then pluck just the lower string — adjust to match. Repeat for all four courses. This is the part that takes longer than tuning a guitar.
5. Cross-check with the other courses. Once all four courses are matched-pair-tuned, pluck adjacent pairs together (G with D, D with A, A with E) — perfect fifths should ring cleanly without beating. If they don't, one course has drifted; recheck and adjust.
6. The reading holds at the stable body of the pluck. As the doubled course decays, a median filter and a stable-pitch lock keep the held reading steady on the body of the note rather than chasing the noisy decay tail. You can pluck, look up at the screen, and read what you played without having to time it perfectly.
Why two strings per course matters
The mandolin's doubled-course design comes from its Italian lute and gittern ancestors — small acoustic instruments that needed maximum volume from minimal size. Doubling each string roughly doubles the amount of vibrating energy fed into the soundboard, making the instrument louder than a single-string equivalent of the same body size.
The second effect is subtler and more interesting: two strings tuned to the same nominal pitch are never exactly the same frequency. Tiny differences in string thickness, age, stretch, and how each one was tuned mean the two strings in a course always differ by a few cents. When plucked together they "beat" against each other at a rate proportional to the cents difference — a few beats per second when nearly perfectly matched, faster when more out of tune.
At very small cent differences (1-3 cents) the beating is too fast to perceive as separate beats — instead it sounds like a smooth, shimmering chorus, similar to the chorusing effect of a 12-string guitar but spread across all four pitch positions. At larger differences (10+ cents) the beating becomes obvious and unpleasant. Getting both strings of each course matched to within a couple of cents is therefore the central craft of mandolin tuning. It takes longer than tuning a single-string instrument, but the payoff is the distinctive bright chime of a well-tuned mandolin.
Same tuning as a violin — and the consequences
The mandolin shares GDAE tuning with the violin exactly — same pitches, same perfect-fifth intervals, same fingering geometry. A trained fiddler can pick up a mandolin and immediately know where every note is. The reverse is also true: mandolinists who switch to fiddle find the left hand fingerings transfer directly.
This is why mandolin and fiddle are so commonly paired in folk traditions — bluegrass, Irish trad, old-time, Cajun. The two instruments cover the same harmonic territory but with totally different timbres (a sustained bowed singing tone vs a percussive plucked attack), so they complement rather than duplicate. A bluegrass mandolinist and fiddler can play in unison and the combined sound is a single voice with both timbres at once.
The other inheritance from violin: tuning in fifths means double-stops at the fifth (playing two adjacent strings simultaneously) produce perfect intervals, which makes the open-string drones in old-time and Irish trad fiddle equally natural on mandolin. The downside is that fifth-tuning is harder to play guitar-style chord shapes on — most chord shapes are derived from fourth-tuning logic. Mandolinists develop their own chord vocabulary built around partial double-stops and tremolo rather than full strummed chords.
Mandolin tuning reference table
| Tuning | Courses (4 → 1) | Frequencies (Hz) | Used for |
|---|---|---|---|
| Standard GDAE | G3 D4 A4 E5 | 196.00 · 293.66 · 440.00 · 659.26 | Classical, bluegrass, Irish trad, jazz — almost all |
| Cross A (AEAE) | A3 E4 A4 E5 | 220.00 · 329.63 · 440.00 · 659.26 | Appalachian old-time, paired with cross-tuned fiddles |
| Open D (DDAD) | D3 D4 A4 D5 | 146.83 · 293.66 · 440.00 · 587.33 | Modal old-time, D-drone heavy repertoire |
| Cajun A (AEAE) | A3 E4 A4 E5 | 220.00 · 329.63 · 440.00 · 659.26 | Cajun, some old-time A-modal tune families |
| Octave mandolin GDAE | G2 D3 A3 E4 | 98.00 · 146.83 · 220.00 · 329.63 | Octave mandolin (a larger sibling instrument) |
| Mandola CGDA | C3 G3 D4 A4 | 130.81 · 195.00 · 293.66 · 440.00 | Mandola — bigger body, tuned a fifth below mandolin |
| Mandocello CGDA | C2 G2 D3 A3 | 65.41 · 97.99 · 146.83 · 220.00 | Mandocello — even larger, one octave below mandola |
Highlighted row is the standard. The bottom three rows are the larger mandolin-family instruments — octave mandolin, mandola, mandocello — which use this tuner's pitch detection too, but you'd need to set the target manually. All are tuned in perfect fifths.
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The mandolin family
The mandolin is the smallest member of a four-instrument family, each tuned in perfect fifths in doubled courses, each an octave below the next-smaller member.
Mandolin — GDAE in the violin range. The standard. About 70 cm long. Used everywhere in folk and acoustic music.
Octave mandolin — GDAE one octave below the mandolin. About 90 cm long. The "Irish bouzouki" is essentially the same instrument with a longer scale. Used heavily in Irish trad and Celtic folk.
Mandola — CGDA, tuned a perfect fifth below the mandolin (same as the viola pitches). About 80 cm. Used in mandolin orchestras and chamber arrangements.
Mandocello — CGDA one octave below the mandola (same pitches as the cello). About 1 m long. Bottom-end member of the mandolin family. Rare outside dedicated mandolin orchestras.
Continue exploring
Sources & technical notes
- Paul Sparks, The Classical Mandolin (Oxford University Press, 1995) — the standard scholarly history of the mandolin in classical and chamber music.
- James Tyler and Paul Sparks, The Early Mandolin (Oxford University Press, 1989) — the standard reference on the mandolin's Italian baroque origins and the development of the modern GDAE doubled-course configuration.
- Roger H. Siminoff, The Luthier's Handbook (Hal Leonard, 2002) — practical reference for mandolin construction, including course-pair tuning practice and bridge intonation.
- Bill Monroe and his Blue Grass Boys (Decca Records, 1939 onward) — the foundational recorded canon of bluegrass mandolin in standard GDAE tuning.
- Mick Moloney, Far from the Shamrock Shore: The Story of Irish-American Immigration Through Song (Crown, 2002) — context for Irish trad mandolin and the closely-related Irish bouzouki / octave mandolin.
- 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, with an octave-down guard that prefers the higher true fundamental when a sub-period is an equally-deep dip.
- The held reading is stabilised by a median filter over recent frames plus a stable-pitch lock: once several consecutive readings agree within ~10 cents, the display locks to that value and releases only on a sustained adjustment, keeping the reading on the body of the note rather than the noisy decay tail.
Eight strings, four courses, GDAE. Same notes as the fiddle in the player's lap next to you. Match both strings of each pair, then tune the rest.