Guitar Tuner Online — Free Acoustic & Electric

Standard guitar tuning is EADGBE, low to high, with the sixth string at E2 (82.41 Hz) and the first at E4 (329.63 Hz) when A4 = 440 Hz. It is the default tuning for most acoustic and electric guitars and the reference point every alternate tuning on this site is described against.

How to use it

1. Start the tuner. Press Start Tuner (Microphone) and allow microphone access. The audio is analysed in your browser; nothing is uploaded.
2. Mute the other five strings. Rest the side of your strumming hand across them. A guitar’s open strings ring sympathetically, and that ringing is the most common reason a reading jumps between notes.
3. Pluck one string, firmly and cleanly. Pluck over the 12th fret with a thumb or soft pick. A gentle pluck near the bridge is thin on the fundamental; a hard pick attack adds noise the detector has to reject.
4. Turn the peg toward the note. A needle left of centre means the string is flat: tighten. A needle right of centre means it is sharp: loosen slightly past the note and come back up to it.
5. Work from the sixth string to the first. Low to high, one string at a time, then re-check all six.
6. Use the hear-tone buttons to train your ear. Each string card can play its own reference pitch, so you can check a string by listening as well as by reading the needle.

Relative tuning without the microphone

If you have no microphone or you are tuning somewhere too noisy, standard tuning can be set from one in-tune reference string using the fret method:

Reference	Fret	Matches
6th string	5th fret	Open 5th string (A2)
5th string	5th fret	Open 4th string (D3)
4th string	5th fret	Open 3rd string (G3)
3rd string	4th fret	Open 2nd string (B3)
2nd string	5th fret	Open 1st string (E4)

The 3rd string uses the 4th fret because the interval between the 2nd and 3rd strings is a major third, not a fourth. Tuning by frets is only as accurate as your starting reference, so confirm the sixth string with the tuner first whenever you can.

Standard tuning string frequencies

Strings are numbered from the player’s point of view: the sixth string is the thickest and lowest, and the first is the thinnest and highest. Every card in the tuner shows both the number and the note.

String	Note	Frequency (A4 = 440 Hz)
6th (thickest)	E2	82.41 Hz
5th	A2	110.00 Hz
4th	D3	146.83 Hz
3rd	G3	196.00 Hz
2nd	B3	246.94 Hz
1st (thinnest)	E4	329.63 Hz

Alternate tunings

Standard tuning is the starting point for every alternate tuning. Each of these pages starts its tuner on the right preset and explains what changes and why:

Tuning	Notes (low → high)	Page
Drop D	D A D G B E	Drop D tuner
Half step down (Eb standard)	Eb Ab Db Gb Bb Eb	Half step down tuner
Open G	D G D G B D	Open G tuner
Open D	D A D F# A D	Open D tuner
DADGAD	D A D G A D	DADGAD tuner
Drop C	C G C F A D	Drop C tuner

For any instrument outside the presets, the chromatic setting in the preset selector above tunes to all twelve notes rather than to a fixed set of strings.

Acoustic and electric guitars

Everything on this page works as an acoustic guitar tuner and as an electric guitar tuner; only the sound reaching the microphone changes.

Acoustic guitars project into the room, so the built-in microphone usually hears them clearly. Pluck once near the 12th fret with a thumb or a soft pick, keep the guitar about a hand’s width from the microphone, and mute the other strings with the side of your hand. Nylon and steel strings share the same frequencies and targets: nylon settles more slowly when new, while steel holds tension longer but is affected by corrosion and sweat. Because the body resonates, a hard strum can keep the whole instrument ringing and pull the reading between notes — one clean pluck beats a chord every time.

Electric guitars are quiet unplugged, which is why players sometimes assume a microphone tuner will not work. Used as an online electric guitar tuner, this page needs nothing but the device you already have: no cable, no audio interface, no app. Move closer to the microphone and pluck firmly, or play through a clean amp at a low volume rather than a distorted one: overdrive pedals add harmonics that the detector has to reject. The neck pickup gives a cleaner fundamental than the bridge pickup, and rolling the tone control back slightly removes the bright edge the detector does not need. If the room is loud or the band is already playing, a clip-on tuner on the headstock is the better tool.

Accuracy and limits

A tuning reading is only as good as the sound reaching the microphone, and on a standard-tuned guitar almost every bad reading has a physical cause:

• The two E strings are two octaves apart. The sixth string is E2 and the first is E4, and they share the note name E. If the wrong one rings while you pluck, the reading can be a correct E at the wrong octave. Mute the other strings and check the reading against the card for the string in your hand.
• The bottom two strings are the weak ones. The sixth and fifth strings put most of their energy into the region where small laptop and phone microphones are least sensitive (typically below ~100 Hz), so they arrive quieter than the top strings even when they sound loud in the room. Pluck them firmly, hold the note, and keep the guitar a hand’s width from the microphone.
• A noisy room competes with the note. Speech, fans, air conditioning and other instruments all produce unstable readings. The volume gate rejects quiet background noise, but it cannot rescue a genuinely loud room, and a clip-on tuner is the better tool on a stage.
• Tuning cannot fix a setup problem. A string that will not hold pitch, or a fret buzz that appears only in one position, is a mechanical issue rather than a pitch one.
• A flickering reading is usually sympathetic ringing. The tuner reports the loudest periodic signal it receives, so a neighbouring string can dominate the frame. Mute the others and pluck once; on an electric guitar, the neck pickup gives a cleaner signal.

Safety

• Tune up to pitch. If a string is sharp, lower it below the target and bring it back up. Approaching from below seats the string on the tuning post and is the standard way to keep it stable.
• Work in small increments near the target. A quarter turn of the peg moves pitch much further than most players expect, especially on the treble strings.
• Never force a stiff peg. If a peg will not turn, the string may be binding in the nut slot. Ease it free rather than applying more force, which is how pegs and strings break.
• Tune to the right octave. The first string target is E4, not E5. Tuning a string an octave above its intended pitch will snap it.
• Give new strings time. Fresh strings stretch for the first few minutes of playing. Tune, play briefly, then re-check.
• Check the whole instrument after tuning. If one string will not hold pitch or the neck buzzes, the cause is usually the setup, not the tuning.

Clip-on tuner or microphone?

A clip-on tuner senses vibration through the headstock, so it ignores room noise and works on a loud stage. A microphone tuner hears the sound the guitar actually produces in the air, which is what this page does; it needs a quieter room but no extra hardware. On a phone, the built-in microphone is the only input available, and across the six strings of standard tuning it is accurate enough for everyday tuning when you mute the others and pluck cleanly. Drop-tuned and extended-range low strings are the hard case for any microphone tuner, because they sit where small microphones are least sensitive.

Free, in the browser, no app

If you searched for a free guitar tuner app, the browser version removes the install step: this page is free, needs no account, and does no in-app purchase. The audio is analysed locally and never uploaded or recorded. On a phone, add the page to your home screen and it opens with one tap, which is as close to an app as a tuner needs to be.

Once you are in tune, practice what you just set up in the free Virtual Guitar Lab: chords, scales, strumming patterns and a fretboard trainer, all in the browser.

Bass players should use the bass guitar tuner instead, which is built around the lower E1–G2 range, and alternate tunings have their own pages listed above.