Free online guitar tuner

A guitar tuner does one job: it listens to a string and tells you how its pitch compares to the note you want. Below is how to get a reliable reading, what standard tuning actually is, the alternate tunings worth knowing, and why a guitar drifts out of tune in the first place.

Standard tuning: the six strings

Standard tuning is the setup almost every guitar method, chord chart, and song assumes. From the thickest, lowest-sounding string to the thinnest, highest one, the open strings are E, A, D, G, B, and E. A common way to remember the order is the phrase “Eddie Ate Dynamite, Good Bye Eddie.” Four of the strings are a fourth apart and one pair (G to B) is a third, and that spacing is what makes standard chord and scale shapes fall under the hand the way they do — which is why it became the default in the first place.

A tuner measures pitch in hertz (Hz), the number of times the string vibrates per second, so a higher number means a higher note. Here is what the tuner aims for on each string, from the 6th (lowest) to the 1st (highest):

• 6th string — E2 — 82.41 Hz. The thickest string, the lowest note.
• 5th string — A2 — 110.00 Hz.
• 4th string — D3 — 146.83 Hz.
• 3rd string — G3 — 196.00 Hz.
• 2nd string — B3 — 246.94 Hz.
• 1st string — E4 — 329.63 Hz. The thinnest string, the highest note, two octaves above the 6th.

The numbers after the note names (E2, A2, and so on) are octaves. The two E strings share a letter name but sit two octaves apart, which is why the low E sounds so much deeper than the high one.

How to tune, string by string

Play one open string at a time and let it ring. The tuner shows the note it hears and whether that note is sharp (too high) or flat (too low). Turn the tuning peg to raise or lower the pitch until the reading sits on the target note, then move to the next string. Work from the low E across to the high E so you cover them in order.

Two habits make the result hold better. First, when a string is close, finish by turning the peg up into the note rather than down to it; tightening to pitch takes the slack out of the gears, so the string is less likely to slip flat. Second, tune all six strings, then check the first ones again. Bringing one string up to pitch changes the tension the neck carries, which nudges the strings you already set, so a second pass is normal.

Reading sharp and flat

The distance between two adjacent notes is divided into 100 units called cents, and a tuner uses them to show how far off you are. A reading a few cents sharp means the string is slightly too high and needs loosening; a few cents flat means it is too low and needs tightening. When the meter centers on the note with no offset either way, the string is in tune. Most people can’t hear an error of a cent or two on a single string, but they can hear it as a wavering, beating sound when two strings play together, which is exactly what tuning removes.

Getting a clean reading

A microphone tuner is only as accurate as the sound it hears, so a few habits make the reading steadier. Tune one string at a time and mute the others with your palm, since two ringing strings confuse the pitch it detects. Play near the middle of the string with an even, medium pluck rather than a hard attack; a sharp pick stroke can briefly read sharp before the note settles. Let the note ring and watch where the meter comes to rest instead of reacting to its first jump. And work in a quiet room, because background noise and nearby speakers give the tuner competing pitches to lock onto.

How to tune without a tuner

If you have no tuner but need the guitar in tune with itself, use relative tuning, also called the fifth-fret method. Start from the low E at a pitch you trust, then press the 6th string at the 5th fret: that note is an A, and it should match the open 5th string, so adjust the 5th string until the two agree. Do the same at the 5th fret of the 5th string to set the open D, and at the 5th fret of the 4th string to set the open G. The one exception is the 2nd string: press the 3rd string at the 4th fret, not the 5th, to set the open B, then use the 5th fret of the 2nd string to set the high E. The guitar won’t be at concert pitch unless your starting string was, but every string will be in tune with the others, which is what matters for playing alone.

Alternate tunings worth knowing

Standard tuning is a starting point, not a rule. Players retune to make certain chords easier, to reach lower notes, or to get the ringing, open sound that slide and fingerstyle guitarists use. A microphone tuner handles all of them, because it reads whatever pitch you play and names the note — you just aim each string at a different target. The common families are drop tunings, lowered standards, and open tunings.

Drop tunings

• Drop D — D A D G B E. Only the low E changes, dropping a whole step to D. It lets you play a power chord on the bottom three strings with one finger and adds a lower note for riffs. Common in rock and metal.
• Drop C — C G C F A D. Drop D moved down another whole step. Heavier and darker, favored in metal and hardcore.
• Drop C# — C# G# C# F# A# D#. A half step above Drop D-and-a-half; a middle ground for heavier rock that keeps the strings from going too slack.
• Drop B — B F# B E G# C#. Very low and thick, usually played with heavier strings or a longer-scale guitar so the low string keeps its tension.

Lowered standard tunings

• Half step down (E♭ standard) — E♭ A♭ D♭ G♭ B♭ E♭. Every string down one semitone. It keeps standard chord shapes, slightly loosens the strings for easier bends, and gives a warmer, slacker tone. Widely used across blues and rock.
• D standard — D G C F A D. Every string down a whole step, for a heavier sound while keeping standard fingerings.
• C standard — C F B♭ E♭ G C. Down two whole steps; low and heavy, common in doom and metal, and best with thicker strings.

Open tunings

In an open tuning the open strings already form a chord, so strumming across all six with nothing fretted sounds a full chord, and a slide or a single barred finger moves that chord up and down the neck.

• Open D — D A D F# A D. The open strings make a D major chord. A staple of slide and folk playing.
• Open G — D G D G B D. An open G major chord, long associated with slide blues and ringing rock rhythm parts.
• Open C — C G C G C E. A wide, resonant C major with a deep low string, used for big fingerstyle arrangements.
• Open E — E B E G# B E. A bright open E major, popular for slide. It raises three strings above standard, so bring them up to pitch gently to avoid over-stressing them.

DADGAD

DADGAD — D A D G A D. Named after its notes, this modal tuning sits between an open and a standard tuning. It isn’t a plain major or minor chord, which leaves it open to both, and its droning, unresolved sound made it a favorite in Celtic and folk fingerstyle as well as some hard rock.

Tuning an electric versus an acoustic guitar

The pitches are the same; the practical details differ. You can tune an electric through a microphone in a quiet room, but you’ll get a cleaner signal by plugging into an audio interface so the tuner reads the pickup directly and ignores the room. On an acoustic, aim the microphone at the soundhole and tune somewhere quiet, since the built-in mic picks up background noise along with the string.

Two physical things affect how well the tuning holds. Brand-new strings stretch for the first hour or two of playing and keep going flat until they settle, so tune, play a little, and retune a few times and they’ll stabilize. String gauge matters too: heavier strings hold lower tunings without going slack but need more finger pressure, while lighter strings are easier to play yet can feel loose and buzz once you tune down. If you drop to a low tuning often, matching the string gauge to it keeps the guitar feeling right.

Why a guitar goes out of tune, and how often to check

A guitar drifts for reasons that have nothing to do with how carefully you tuned it. Wood expands and contracts with temperature and humidity, which changes the neck and the string tension, so a guitar left by a window or carried in from the cold will read off. Hard strumming and bends pull strings sharp or flat over a set, and worn strings hold pitch poorly. The practical answer is to check the tuning at the start of every session, and again whenever something sounds off, rather than trusting that yesterday’s tuning survived the night.

What a chromatic tuner is

This tuner is chromatic, meaning it recognizes all twelve notes rather than only the six of standard tuning. That is what lets it handle every alternate tuning above: it names the nearest note to whatever you play and shows how far off you are, so you can bring any string to any target you choose.