Music Hub › Guides › Instrument technique › Standard Guitar Tuning: Why E-A-D-G-B-E

The six strings, from lowest to highest

Standard tuning puts six notes on the six strings of the guitar, from the lowest string (the thickest, numbered 6) to the highest (the thinnest, numbered 1): E, A, D, G, B, E. The two E strings do not ring at the same pitch: the first, on the thickest string, is the lowest E on the whole instrument; the second, on the thinnest string, rings exactly two octaves higher, four times its frequency. Between them sit four strings, A, D, G and B, which fill out the tuning and give the instrument its full range, a little over three and a half octaves open on a standard twenty-fret neck.

Memorizing this order takes a bit of repetition. A classic mnemonic phrase circulates widely in guitar teaching, built from the first letter of each string, one word per string from the low E to the high E, something like "Eddie Ate Dynamite, Good Bye Eddie." Beyond any specific phrase, the most reliable trick is simply to sing the six notes aloud, in order, until they become as automatic a reflex as counting to six.

The perfect fourth: the interval that structures the neck

An interval measures the gap between two notes in half steps, the smallest step used by the twelve-note Western system. Between E and A, between A and D, between D and G, and again between B and the high E, that gap is five half steps: a perfect fourth, the same interval repeated four times across the five neighboring string pairs. This regularity is no accident of instrument building: it lets a single finger pattern, for a scale or a chord, carry over almost unchanged from one string to the next, with a simple horizontal shift along the neck rather than a whole new fingering.

That same regularity also serves as a reference point for tuning the instrument without a tuner. On any given string, the note played at the 5th fret matches the next string played open, since five frets equal five half steps, a perfect fourth. This reference, detailed further on in the by-ear tuning method, works for four of the five neighboring string pairs; the fifth needs a different number, the exception covered in the next section.

Tuning almost entirely in fourths is not universal among string instruments: the violin, viola and cello are tuned in fifths, an interval two half steps wider, which maximizes the range of notes reachable without shifting the hand but demands a wider finger stretch on each string. On a guitar neck, wider than a violin's and carrying six strings rather than four, the perfect fourth remains the interval that best balances the range of accessible notes against the comfort of the left hand.

The exception between G and B: a major third, and why it exists

Between the 3rd string (G) and the 2nd string (B), the rule of perfect fourths stops dead: the gap is only four half steps, a major third, one half step narrower than everywhere else on the neck. It is the single irregularity in the whole standard tuning, and it breaks the perfect symmetry the perfect fourth sets up between the other four string pairs.

This exception has very concrete consequences for the hands. A scale pattern or chord shape that otherwise repeats identically from string to string has to shift up by one extra fret at the exact moment it crosses the G-B pair. This tuning detail, and this alone, is why E-shape barre chords do not follow a perfectly regular pattern across all six strings: the Music Hub's guide on mastering barre chords covers the mechanics of those shapes without revisiting this underlying cause, which lies entirely in the tuning itself, not in the shape of the hand.

Why did luthiers not simply keep a perfect fourth everywhere, for total regularity? The answer is an ergonomic trade-off inherited from the plucked string instruments of the Renaissance, covered in the next section: a tuning built entirely from perfect fourths across six strings would demand a wider hand stretch for certain very common open chords, whereas a slight narrowing, at this one specific spot on the neck, makes several left-hand positions more comfortable instead.

Why this tuning was chosen: the Renaissance vihuela and lute

This structure's origin reaches back well before the modern guitar, to the Renaissance vihuela and lute, two plucked string instruments that dominated Spanish and European art music in the 15th and 16th centuries. Both instruments already shared an almost identical tuning principle: a run of perfect fourths between neighboring strings, interrupted by a single major third in the middle of the series. The guitar did not invent the G-B exception; it inherited it from a much older convention, common to a whole family of plucked string instruments.

The five-course guitar, five pairs of strings, that circulated in Italy and Spain from the 16th century onward carried this logic over almost unchanged, tuned A-D-G-B-E, exactly the five higher strings of today's modern guitar. When the six-single-string instrument gradually took over during the 18th century, replacing the doubled courses with single strings, it seemed more logical to add an extra low E to extend the same logic of fourths downward, rather than inventing an entirely different tuning for a single extra string.

This historical continuity is no fixed dogma: even today, it answers a genuine ergonomic trade-off rather than pure habit. A tuning built entirely from perfect fourths, with no third at all, would slightly widen the range of notes reachable without moving the hand, somewhat like a violin tuned in fifths but narrowed to stay playable on a guitar's wider neck. At the same time, the open strings E-A-D-G-B-E hand you easy triads within the very first frets, which made open chords feel natural and comfortable from the earliest days of the modern instrument, and explains why this convention, passed down from the lute to the vihuela and then to the guitar, has never really been challenged since.

The physics of the string: tension, length and mass per unit length

What the ear perceives as the pitch of a plucked string, lower or higher, depends entirely on three physical quantities that a luthier and a guitarist manipulate, consciously or not, every time they set up the instrument: the tension applied to the string, its vibrating length, meaning the portion that can actually oscillate between the nut and the bridge, and its mass per unit length, the mass of material per unit of length, which depends on the string's diameter and the material it is made of.

These three quantities and their effect on perceived pitch were formalized in the 17th century by the French mathematician, music theorist and theologian Marin Mersenne (1588-1648), in his encyclopedic treatise Harmonie universelle (Universal Harmony), published in 1636 and 1637. In it, Mersenne demonstrates experimentally, by measurement and not just by reasoning, three relationships that even Galileo, who had anticipated them theoretically, considered impossible to verify concretely for lack of measuring instruments precise enough in his era. This experimental feat is why these three relationships are known today as Mersenne's laws, a bridge between the Pythagorean tradition, which already linked music to ratios of whole numbers, and modern experimental acoustics.

Mersenne's laws are simple to state, and you do not need to handle the formula to understand them: a string's frequency increases with the square root of its tension, a string pulled twice as tight does not sound twice as high but around 1.4 times as high; it decreases as the vibrating length increases, in a direct inverse relationship, a string twice as long sounds exactly one octave lower at equal tension; and it decreases with the square root of the mass per unit length, which is why a guitar's bass strings are wound, wrapped with an extra layer of metal wire, to gain mass without becoming too stiff or too tight. For anyone who likes notation, the full formula reads f = (1 / 2L) times the square root of (T / μ), where f is frequency, L the vibrating length, T the tension and μ the mass per unit length; but remembering the three relationships in words is plenty to understand why a luthier only has these three levers, and no others, to set a string's pitch.

It is exactly the combination of these three parameters, on a neck of fixed length, that gives each string of the standard tuning its precise frequency in Hertz, the unit that measures the number of vibrations per second. The table below details all six, tuned to the international reference of A at 440 Hz.

The ratio between two neighboring frequencies confirms what interval theory predicts: between the low E and the A, as between the other pairs in a perfect fourth, the frequency is multiplied by a factor of about 1.335, the frequency equivalent of five half steps in equal temperament; between the G and the B, the factor drops to about 1.260, that of a major third of only four half steps, very slightly tighter.

Tuning your guitar: tuner, app, or by ear

Three families of tools let you tune a guitar today, from the most reliable to the most demanding on the ear. The electronic tuner, either a clip-on (fixed to the headstock, it picks up the vibrations of the wood) or one with a built-in microphone, remains the gold standard for reliability: it displays the exact gap to the target note, in cents, the unit that divides each half step into a hundred equal parts, and it works in any conditions, including on stage amid ambient noise. A mobile app does essentially the same thing through the phone's microphone, with accuracy close to a dedicated tuner in a quiet environment, which makes it a practical fallback when you do not have a physical tuner on hand.

Tuning by ear remains a worthwhile skill to build, if only to double-check a suspect tuner or get by with no tool at all. The so-called 5th fret method relies directly on the perfect fourth covered above: play the 5th fret of a string, it should sound exactly like the next string played open; adjust the tuning peg until the two notes merge, with no perceptible beating between them. Repeat string by string starting from the low E. The one exception to remember, already flagged above: between the G string and the B string, compare the 4th fret rather than the 5th, since the interval there is the narrower major third.

The harmonics method sharpens the ear's precision even further. A natural harmonic, produced by touching the string lightly rather than pressing it down, exactly above a fret like the 5th or the 7th, isolates a pure, simple component of the string's sound, stripped of the fundamental's complexity, and so rings longer and more clearly than a normally fretted note. Comparing the harmonic at the 5th fret of one string to the harmonic at the 7th fret of the next, higher string, the ear picks up even the slightest beating, that flutter caused by two frequencies that are almost but not quite identical, and can fine-tune with a precision beyond what open strings allow. One technical caveat is worth knowing: because harmonics produce perfectly pure intervals while the guitar neck is built for equal temperament, a pair of harmonics tuned to perfection with this method sometimes leaves the G string very slightly off from theoretical equal temperament, a gap too fine for the ear but measurable on a tuner.

That leaves the question of the reference pitch itself: at exactly what frequency should the A on the 5th string be tuned? The international standard ISO 16, recommended as early as 1939 and formalized in 1955 and then 1975, sets concert pitch at 440 Hz, the value followed by nearly all amplified music and most orchestras. Some orchestras, particularly in continental Europe, tune noticeably higher by tradition: the Vienna Philharmonic sits close to 443 Hz, and many orchestras on the continent fall between 440 and 444 Hz, a choice that gives a sound perceived as slightly brighter. For a guitarist not playing alongside an orchestra tuned to that reference, 440 Hz remains by far the standard to follow.

New strings: why they slip out of tune and how to break them in

A guitar that has just been fitted with a fresh set of strings slips out of tune almost every time you pick it up again, sometimes so noticeably that beginners assume the instrument is faulty. There is nothing abnormal about it: it comes down to how a new string mechanically settles at three specific points. Around the tuning post, where it is still wound a little loosely right after installation; at the nut, where it needs to bed into its slot; and at the bridge or the ball-end anchor, depending on the type of guitar, where it finishes seating itself under tension. Until these three contact points have finished settling, the string keeps stretching slightly every time you play or retune it, and so keeps dropping in pitch between sessions.

Breaking in a string is precisely about speeding up that settling rather than waiting it out passively. After fitting and roughly tuning each new string, simply pull it gently, perpendicular to the neck, along its whole length, then retune it: this simple move forces, all at once, the stretch that several days of normal playing would otherwise produce bit by bit. Repeating the move three or four times, string by string, is usually enough to settle a set of wound steel strings, the most common type on folk or electric guitars, within one to two hours of playing or active stretching combined. Nylon strings on a classical guitar, more elastic by nature, need noticeably more patience: they usually take around forty-eight hours of active playing to fully settle, sometimes spread over two to four days, before the tuning really holds from one session to the next.

This break-in period is also why it is best to avoid changing all your strings right before an important concert or recording session: better to fit them at least the day before, breaking them in actively, than to discover live that they keep dropping between songs.

How often to retune: temperature, humidity and worn strings

Even a perfectly broken-in guitar that has been set up for months never stays in tune indefinitely, for reasons that have nothing to do with the instrument's quality. Temperature is the first cause: a swing of around 5 to 6°C (9 to 11°F) is enough to change the string tension and the neck wood's geometry enough to shift the tuning by several cents, easily audible to a trained ear. A guitar pulled from a cold case into a heated room, or left in direct sun behind glass, will therefore drift out of tune almost every time until it settles back to a stable temperature.

Humidity plays a role just as real, but slower and more insidious. The wood of the neck and the top absorbs or releases ambient moisture depending on the climate: air that is too dry shrinks the wood, which tends to raise the tension and so the pitch of the strings, while air that is too humid swells it, changes the string height above the frets and can slightly shift the bridge's position, which affects both the tuning and the intonation across the whole neck. The recommended range for most guitars sits around 40 to 55% relative humidity, at an ambient temperature of roughly 21 to 26°C (70 to 79°F): outside that range, beyond simply going out of tune, the wood itself eventually warps in a lasting way.

The strings themselves age, independent of climate. Finger sweat, skin oils and dust gradually build up in the windings of wound strings, which dampens their vibration, particularly in the highs, and costs clarity, sustain and pitch stability: a corroded, grimy string holds its tuning noticeably worse than a clean, new one, even with no measurable change in tension. How often you play matters too: strings played every day, with a hard pick or a heavy attack, wear out and corrode faster than strings played occasionally with a soft pick. In practice, most guitarists change their strings every two to six months depending on how often they play, or as soon as the strings look dull, feel rough to the touch, or plainly get harder to keep in tune from one day to the next.

Alternate tunings in brief: drop D and open tunings

Standard tuning is not a fixed constraint: once it is well mastered, there is a whole family of alternate tunings that deliberately change one or more strings for different sounds or to simplify certain playing styles. The closest to standard, drop D, touches only one string: the low E drops a whole step down to D, which turns the three lowest strings into an open, playable power chord, widely used in rock and metal, but also in blues, folk and even the classical repertoire.

Open tunings go further: every string is retuned so that all six played open already ring out a complete chord, with no finger touching the neck. Open D tuning (D-A-D-F♯-A-D) is particularly associated with bottleneck or slide playing, where sliding an object along the open strings becomes instantly musical; open G tuning (D-G-D-G-B-D) remains iconic in rock and electric blues. These are just two examples from a much wider family of open tunings, each built for a specific style or effect, and this guide is not meant to cover them in detail: each deserves its own exploration, once standard tuning, with its perfect fourth and its G-B exception, has become second nature.

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