Free Online Guitar Tuner
Tune by ear or with your microphone: E Standard, Drop D, Half-Step Down, Open G, or a custom tuning — with a cents readout that goes green within ±3 cents. Everything runs in your browser; your mic input is analyzed locally and never recorded or uploaded.
E A D G B E — the default tuning for nearly all guitar music
Your browser will ask for microphone access. Audio is analyzed on your device only.
Waiting for a note…
How to Tune Your Guitar
- 1Start with the low E (6th) string and work up to the high E — going low to high keeps tension changes from pulling earlier strings out again.
- 2Pluck the string openly and let it ring: the string closest to your note lights up, and the meter shows whether you are flat (loosen) or sharp (tighten).
- 3Turn the tuning peg slowly in small moves while the string still rings, and watch the needle settle toward the green ±3-cent zone.
- 4Stretch new strings gently and re-check: fresh strings drift flat for the first few tunings as they settle.
- 5Always re-check all six strings once at the end — changing one string’s tension slightly shifts the neck’s pull on the others.
Standard Tuning Frequencies & Common Alternate Tunings
Frequencies are equal-tempered against A4 = 440 Hz. A cent is 1/100 of a semitone — most people can hear about 5–10 cents of error on a sustained note, which is why this tuner flags ±3 cents as in tune.
| Tuning | Strings (6→1) | Frequencies (Hz) |
|---|---|---|
| E Standard | E2 A2 D3 G3 B3 E4 | 82.4 / 110.0 / 146.8 / 196.0 / 246.9 / 329.6 |
| Drop D | D2 A2 D3 G3 B3 E4 | 73.4 / 110.0 / 146.8 / 196.0 / 246.9 / 329.6 |
| Half-Step Down (E♭) | D♯2 G♯2 C♯3 F♯3 A♯3 D♯4 | 77.8 / 103.8 / 138.6 / 185.0 / 233.1 / 311.1 |
| Open G | D2 G2 D3 G3 B3 D4 | 73.4 / 98.0 / 146.8 / 196.0 / 246.9 / 293.7 |
Who Plays in These Tunings?
Drop D
A staple of rock, grunge, and metal — from folk fingerstyle to heavy riffing — because the low D powers one-finger power chords.
Half-step down (E♭)
Stevie Ray Vaughan and Jimi Hendrix famously tuned down a semitone for a looser, warmer string feel and easier bends.
Open G
Keith Richards built the Rolling Stones’ guitar sound on Open G (D–G–D–G–B–D), often with the sixth string removed entirely.
Related Audio Tools
Quick Answer
To tune a guitar, allow microphone access, play an open string, and turn the tuning peg until the tuner shows the string in tune — flat means tighten, sharp means loosen. This free online guitar tuner detects pitch through your microphone with ±3-cent accuracy, auto-finds the closest string, and ships E Standard (E A D G B E), Drop D, Half-Step Down (E♭), Open G, and fully custom tunings, plus a reference tone on every string for tuning by ear. All audio is analyzed on your device and never recorded or uploaded.
How It Works
Click Start and allow microphone access — your browser may prompt once; audio is processed on your device only
Pick a tuning: E Standard, Drop D, Half-Step Down, Open G, or Custom (set any note and octave per string)
Play the low E string openly and let it ring — the closest string chip lights up automatically
Turn the tuning peg slowly until the needle sits in the green ±3-cent zone: flat means tighten, sharp means loosen
Repeat from the A string up to the high E, then re-check all six strings once to catch tension drift
Key Facts
- Microphone pitch detection accurate to ±3 cents — the green zone on the meter
- Four built-in tunings: E Standard, Drop D, Half-Step Down (E♭), and Open G
- Custom mode: set any note and octave for each of the six strings
- Auto-detects the closest string to whatever you play and shows flat/sharp direction
- Reference tones for every string, so you can also tune by ear
- Equal-temperament frequencies computed live from A4 = 440 Hz
- Raw signal path: browser echo cancellation and noise suppression are disabled so pitch stays accurate
- 100% client-side — your microphone input is analyzed locally, never recorded or uploaded
Frequently Asked Questions
How do I tune a guitar with an online tuner?
Click Start, allow microphone access, then play your low E string openly and let it ring. The chip for the closest string lights up and the meter shows whether you are flat (tighten the peg to raise the pitch) or sharp (loosen it). Adjust the peg slowly until the needle sits in the green ±3-cent zone, then repeat for A, D, G, B, and high E. Always finish by re-checking all six strings once, because changing one string shifts the neck tension slightly.
What are the frequencies of the six guitar strings in standard tuning?
In E Standard (A4 = 440 Hz) the open strings are E2 = 82.41 Hz, A2 = 110.00 Hz, D3 = 146.83 Hz, G3 = 196.00 Hz, B3 = 246.94 Hz, and E4 = 329.63 Hz. Each fret raises a string by one semitone, a factor of 2^(1/12) ≈ 1.0595. This tuner computes every target from A4 = 440 Hz in equal temperament, the same system guitars are fretted for.
What is a cent, and how accurate should a guitar tuning be?
A cent is one hundredth of a semitone — 1/1200 of an octave. Most listeners can hear 5–10 cents of error on a sustained note, and guitars sound noticeably sour when strings are more than about 5 cents off, which is why this tuner marks ±3 cents as in tune. Mechanical tuners rarely settle better than ±1–2 cents anyway; getting every string within ±3 cents is well below what your audience can hear.
How do Drop D, Half-Step Down, and Open G tunings differ?
Drop D lowers only the sixth string a whole step, E2 → D2 (73.42 Hz), so the bottom three strings form a power chord with one finger. Half-Step Down (E♭) drops all six strings one semitone (E♭ A♭ D♭ G♭ B♭ E♭) — Stevie Ray Vaughan and Jimi Hendrix used it for a looser, warmer feel. Open G retunes to D G D G B D so strumming open strings rings a G major chord — the foundation of Keith Richards’ style. All three are built into this tuner, plus a custom mode for anything else.
Why does my tuner struggle with the low E string?
Low pitches have long periods (E2 is 82 Hz — about 12 milliseconds per cycle), so the detector needs a long enough sample to see several full cycles, and the fundamental is often weaker than the harmonics on a thick string. Pluck firmly near the 12th fret, let the note ring, and tune to the reading that stabilizes after the attack. This tuner analyzes 85 ms of audio per update, enough for several cycles even of a dropped-D low string.
Is this guitar tuner free and private?
Yes — completely free, with no sign-up or install. Your microphone signal is analyzed locally in your browser by the Web Audio API and is never recorded, stored, or uploaded. The tab even asks for a fresh permission each visit, and you can revoke access at any time from the icon in your browser’s address bar.