Mandolin and Banjo Tuning Explained (GDAE and Open G)

The mandolin and the five-string banjo sit at the heart of bluegrass and folk, and each breaks the “strings go low to high in order” rule in its own way: the mandolin doubles every note, and the banjo hangs its highest string above everything else — starting halfway up the neck. Both tune quickly with a chromatic tuner once you know the logic.

Mandolin: four notes, eight strings

A mandolin has eight strings arranged in four courses — pairs tuned in perfect unison. The courses are tuned G3–D4–A4–E5, low to high: identical to a violin, in perfect fifths. If you ever forget, it’s the guitar’s G–D–A–E bottom four reversed in interval direction — fifths going up instead of fourths.

The pair problem — and the routine that solves it

The whole art of mandolin tuning is getting each pair perfectly matched. Two strings a few cents apart don’t sound like two notes — they sound like one sour, warbling note, and eight strings give you four chances to warble. The routine:

1. Mute one string of the pair with a spare fingertip and tune its partner alone to the chromatic tuner — letter first, then center the needle. Tuning both at once confuses the tuner and your ear.
2. Swap: mute the tuned string, tune its twin the same way.
3. Then play both together and listen. Perfectly matched pairs “lock” into a single bright note. Any slow wah-wah-wah pulse means they’re a few cents apart — beats, the same phenomenon we use in ear tuning. Nudge one string until the pulse slows and stops.
4. Work through the courses G → D → A → E, then do a full second pass — eight strings’ worth of tension changes add up.

Five-string banjo: the drone on top

Standard bluegrass banjo tuning is Open G: g4–D3–G3–B3–D4. Strummed open, it sounds a G major chord — same idea as Open G guitar. The oddity is the 5th string, written with a lowercase g: it is a drone string that starts at the fifth fret, runs alongside the neck to its own little tuning peg, and is tuned to G4 — the highest pitch on the instrument despite being the “5th” string. That high drone ringing through everything is the signature banjo sound. There’s also a dedicated banjo tuner page with these targets built in, if you’d rather start there.

Banjo tuning order and quirks

1. Tune the four long strings first: D3 → G3 → B3 → D4. Letter and octave first, then the needle — the 1st and 4th strings are both D, an octave apart, so the octave display matters.
2. Tune the 5th string to G4 last. Its short scale makes it twitchy — small peg moves, and re-check twice, since some 5th-string pegs (especially friction pegs) like to slip.
3. Check with the open strum: a clean G major chord. Then fret the whole chord at the 2nd fret (an A chord) and listen again — a banjo that’s sweet open but sour fretted usually has a bridge position problem, not a tuning problem.

Microphone tips for both instruments

• Both instruments are loud and percussive — pluck gently while tuning so the attack transient doesn’t swamp the reading.
• Mandolin E strings at 659 Hz are far above guitar range; if your tuner seems to hesitate up there, pluck closer to the fingerboard for a rounder tone.
• A banjo’s head resonates with room noise more than a wooden top does. Tune away from fans and chatter, or damp the head lightly with your forearm while tuning single strings.
• The rest is the standard ritual: one string at a time, approach from below, second pass always.

Frequently asked questions