🎸 Guitar Tuner
Tune your guitar, bass or ukulele with your microphone. Standard, Drop D, DADGAD, open and half-step-down tunings, a cents meter and reference tones.
What Guitar Tuner Does
This online guitar tuner listens through your microphone and shows the note you are playing, the target note for your chosen tuning, and how many cents sharp or flat you are. It covers standard tuning, Drop D, half-step down, Open G, Open D and DADGAD on guitar, plus standard bass and ukulele and a chromatic mode for any instrument.
Guitar strings are tricky to track because the second harmonic is often louder than the fundamental, which makes simple tuners jump an octave. This one uses the McLeod Pitch Method, which normalizes the signal’s self-similarity and picks the first strong period rather than the loudest one, then interpolates between samples for sub-cent resolution. Browser noise suppression is switched off while tuning, because it distorts pitch.
Each string also has a reference tone you can play, for tuning by ear or for checking the tuner against a note you trust.
How to Use Guitar Tuner
- Choose your instrument and tuning
- Press Start and allow microphone access
- Pluck one string and let it ring
- Turn the peg until the needle is centered and the note turns green
- Tap a string button to hear its reference pitch if you prefer to tune by ear
Formula Used by Guitar Tuner
Note frequencies in equal temperament
f = A4 × 2^((n − 69) ÷ 12)
- n
- MIDI note number: A4 = 69, middle C = 60, low E on guitar = 40
- A4
- Reference pitch, 440 Hz by international standard (ISO 16)
Worked example
Low E string, E2 = note 40.
- 440 × 2^((40 − 69) ÷ 12) = 440 × 2^(−2.4167)
Result: 82.41 Hz
How far off you are, in cents
cents = 1200 × log₂(measured ÷ target)
Worked example
The A string reads 111 Hz; target 110 Hz.
- 1200 × log₂(111 ÷ 110) = 1200 × 0.01306
Result: +15.7 cents sharp — loosen the string slightly.
Guitar Tunings and String Frequencies (A4 = 440 Hz)
Low (thickest) string first.
| Tuning | Notes | Frequencies (Hz) |
|---|---|---|
| Standard | E2 A2 D3 G3 B3 E4 | 82.41 · 110.00 · 146.83 · 196.00 · 246.94 · 329.63 |
| Drop D | D2 A2 D3 G3 B3 E4 | 73.42 · 110.00 · 146.83 · 196.00 · 246.94 · 329.63 |
| Half step down | E♭2 A♭2 D♭3 G♭3 B♭3 E♭4 | 77.78 · 103.83 · 138.59 · 185.00 · 233.08 · 311.13 |
| Open G | D2 G2 D3 G3 B3 D4 | 73.42 · 98.00 · 146.83 · 196.00 · 246.94 · 293.66 |
| DADGAD | D2 A2 D3 G3 A3 D4 | 73.42 · 110.00 · 146.83 · 196.00 · 220.00 · 293.66 |
| Bass standard | E1 A1 D2 G2 | 41.20 · 55.00 · 73.42 · 98.00 |
| Ukulele standard | G4 C4 E4 A4 | 392.00 · 261.63 · 329.63 · 440.00 |
How to Read Your Result
How close is close enough?
Within ±5 cents the tuner shows green; few listeners can hear a single note that far off. Because a cent is a ratio, it is a much smaller step in hertz on low strings: one cent is about 0.05 Hz at low E and about 0.25 Hz at A4, which is why tuners measure in cents rather than hertz.
440, 442 or 432?
A4 = 440 Hz is the international standard (ISO 16:1975). Some orchestras tune slightly higher, around 442 Hz, and some musicians prefer 432 Hz; the reference slider covers 430–450 Hz so you can match a piano, a backing track or your band. What matters most is that everyone uses the same reference.
Limitations & Accuracy Notes
- It detects one note at a time — strum a chord and the reading will jump. Pluck and let a single string ring.
- Very noisy rooms, distant laptop microphones and heavily distorted guitar tones reduce accuracy.
- It tunes open strings only; intonation (whether fretted notes are in tune) needs a separate check at the 12th fret.
Frequently Asked Questions
How do I tune my guitar with this online tuner?
What are the notes of standard guitar tuning?
What is a cent?
Why does the tuner jump around or show the wrong note?
Should I tune up or down to the note?
What is A4 = 440 Hz, and when would I change it?
Can I tune a bass or ukulele?
References & Further Reading
- McLeod & Wyvill — “A Smarter Way to Find Pitch” (ICMC 2005) — The pitch detection method used
- ISO 16:1975 — Acoustics — Standard tuning frequency — A4 = 440 Hz