Play a string and see its note and how many cents sharp or flat it is. Five tunings, a chromatic mode and reference tones.
An online guitar tuner listens through your microphone, measures the pitch of the string with the YIN algorithm, and shows the nearest note and how many cents sharp or flat it is. Every 70 milliseconds the page reads a block of 4096 samples, about 85 ms of sound at 48 kHz. YIN compares the block with copies of itself shifted by different lags, normalises the differences, and takes the first lag where the difference dips below 0.15 as the length of one period. A parabola through the dip gives the lag between whole samples, and the pitch is the sample rate divided by that lag. The tuner looks for pitches from 50 to 1200 Hz and shows the median of the last 5 readings, so one wrong block does not make the needle jump. A worked example: a string measured at 84 Hz in standard tuning is nearest the low E string, E2 at 82.41 Hz. The distance is 1200 times log2(84 / 82.41), about 33 cents sharp, so you tune down.
Notes follow twelve-tone equal temperament with A4 set to 440 Hz: the frequency of a note is 440 times 2 to the power of (n - 69) / 12, where n counts semitones and A4 is 69. A semitone is 100 cents and an octave is 1200 cents. This tool calls a string in tune when it is within 5 cents of the target; that threshold is the tool's own choice, not a standard. Standard tuning is 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. Drop D lowers the sixth string to D2, 73.42 Hz. DADGAD is D2 A2 D3 G3 A3 D4. Open G is D2 G2 D3 G3 B3 D4. Half step down is every string one semitone lower: Eb2 Ab2 Db3 Gb3 Bb3 Eb4. In Guitar mode the string of the chosen tuning nearest in pitch is the target. Chromatic mode simply names the nearest note.
Pluck one string at a time, let it ring, and keep the microphone a short distance from the sound hole or amplifier. While the tuner listens it turns off echo cancellation, noise suppression and automatic gain in the browser, because those filters change the sound the pitch is measured from. Blocks quieter than an RMS level of 0.01 are treated as silence. A tuner measures the sound, not the string tension, so a new string that keeps drifting will need tuning again. Each string has a reference tone button that plays a sine wave at the target pitch for 3 seconds, which you can match by ear. The reference pitch for A4 can be set from 410 to 470 Hz under Reference pitch, and every note and string is worked out from it.
It hears one note at a time, so strumming a chord gives no reading. It does not take a cable input, only the microphone. It cannot read pitches below 50 Hz, which includes the low E1 of a four-string bass at 41.20 Hz, and a tone above 1200 Hz may be read as a lower multiple of its period. Room noise, a weak phone microphone or a very quiet string can give no reading or a wrong one, and the tool states no accuracy figure because it depends on your microphone and room. Tunings come from English Wikipedia's pages on guitar tunings, DADGAD and Open G; there are many more, and a custom tuning is not offered.
Press Start and allow the microphone, choose Standard, then pluck the open sixth string and let it ring. If the status says Flat, tighten the string; if it says Sharp, loosen it. Repeat for A2, D3, G3, B3 and E4, which are the strings from lowest to highest.
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, with A4 at 440 Hz. Each string button on this page plays its own pitch for 3 seconds so you can match it by ear.
Choose Drop D and play the sixth string while turning its peg down a whole tone from E2 (82.41 Hz) to D2 (73.42 Hz). The other five strings stay as in standard tuning, so the tuner checks them against A2, D3, G3, B3 and E4.
The block was too quiet (below an RMS level of 0.01), the pitch is below 50 Hz, the room is noisy, or the browser blocked the microphone. Pluck harder, move closer, play one string only, and check the lock icon in the address bar for microphone access.
A cent is one hundredth of a semitone, and 1200 cents make an octave. A string 12 cents sharp is 12 hundredths of a semitone above its target. This tuner treats anything within 5 cents either way as in tune.
No. The sound is analysed in your browser as it arrives and is not recorded, saved or sent anywhere. The mode, tuning and reference pitch are saved in this browser so they are there next time. The page counts visits with Google Analytics, never audio or notes.