Tune guitar, bass, ukulele, cavaquinho and other instruments with your microphone, using a cents needle and alternate tunings.
The tuner listens to your microphone and measures the fundamental frequency of the note you play, that is, how many times per second the string vibrates. It uses a normalized autocorrelation, the idea behind the McLeod pitch method: the program looks for the time interval at which the sound repeats and converts that interval to Hz. This gets the note right even when the harmonics are louder than the fundamental, which is common for low notes picked up by small microphones. The analysis window is about 170 milliseconds, long enough for the bass low E (41.2 Hz, a 24 ms period) and short enough for the needle to follow the string. From the frequency, the tuner finds the nearest note in equal temperament, where each octave has 12 semitones of 100 cents and A4 is 440 Hz (the ISO 16 standard). The needle shows the deviation in cents, from 0 to ±50. When the string is within ±5 cents (you can pick ±3 or ±10), the panel turns green and the string is marked as tuned. Everything runs in your browser, with nothing to install and no audio sent anywhere.
With A4 at 440 Hz, the open strings of a guitar are: E2 (6th string) 82.41 Hz, A2 110.00 Hz, D3 146.83 Hz, G3 196.00 Hz, B3 246.94 Hz and E4 (1st string) 329.63 Hz. A 4-string bass sits an octave below the four low guitar strings: E1 41.20 Hz, A1 55.00 Hz, D2 73.42 Hz and G2 98.00 Hz. A 5-string bass adds a low B0 at 30.87 Hz.
Standard ukulele is G4, C4, E4 and A4 (392.00, 261.63, 329.63 and 440.00 Hz). The tuning is re-entrant: the thinnest string is not the highest, because the G sits above the C. The low G variant swaps G4 for G3, an octave lower. The Brazilian cavaquinho uses D4, G4, B4 and D5 (293.66, 392.00, 493.88 and 587.33 Hz). The violin is tuned in fifths: G3, D4, A4 and E5 (196.00, 293.66, 440.00 and 659.26 Hz).
In Drop D only the lowest string goes down a whole step, from E2 to D2, and the other five stay as in standard tuning. It is common in rock and metal because one finger makes a power chord on the three low strings. In half step down, all six strings drop a semitone (E flat, A flat, D flat, G flat, B flat, E flat), which lowers the tension and makes bends easier. DADGAD tunes the strings to D, A, D, G, A, D, an open tuning widely used in Celtic and folk music.
Open tunings make the open strings sound a chord. Open G is D, G, D, G, B, D (a G major chord). Open D is D, A, D, F sharp, A, D (D major). Open E is E, B, E, G sharp, B, E (E major). The capo setting moves every string up by semitones, so you can tune the instrument with the capo already placed on the chosen fret.
In Brazil the cavaquinho is usually tuned D, G, B, D (DGBD, lowest to highest). There is also DGBE, used for solo parts, and CGAD, common in Portugal. The viola caipira has five courses of paired strings. The cebolão in E uses the notes E, B, G sharp, E, B, and the cebolão in D uses D, A, F sharp, D, A, giving an open major chord. Because the strings of each course are paired in octaves and the octave varies between instruments and players, the tuner compares only the note name in these tunings. If your viola uses another tuning, use the chromatic mode.
The tuner measures one note at a time. If two strings ring together, or music is playing in the background, the reading may jitter or not appear. Phone and laptop microphones usually pick up very low frequencies poorly, so on a bass it helps to play harder, bring the device closer or, with an electric bass, place it near the amplifier. Very old strings, or strings off by more than half a step, can be mistaken for the neighboring string: in that case lock the string by tapping the button with its name.
These references help contextualize formulas, standards, APIs and limitations used on this page. They do not replace professional validation when a result has legal, financial, medical or operational impact.
Click Turn on microphone, allow access and pick Guitar. Pluck the open 6th string (the thickest): the tuner shows the note and the cents. If the needle goes left the string is flat and you tighten the tuning peg; if it goes right, you loosen it. Stop when the panel turns green and move on to the next string. When you finish, go back to the first one, because string tension redistributes along the neck.
Turn on the microphone and pluck an open string.
Microphone sound is analyzed on your device, in real time. Nothing is recorded and nothing is sent to servers.