Chromatic Tuner

This is a free chromatic tuner that listens through your device's microphone and shows the note you are playing, its exact frequency in hertz, and how many cents sharp or flat you are on a live needle. It has built-in string maps for guitar (standard EADGBE, Drop D and half-step-down), bass, five-string bass, ukulele, violin, cello, mandolin and banjo — or you can leave it in Chromatic mode to tune piano, vocals, brass and anything else across the full range. All audio is analysed on your device and never leaves the browser.

Under the hood the tuner uses a pitch-detection method based on the normalized square-difference function — the McLeod Pitch Method — which autocorrelates the incoming waveform to find its fundamental period. That approach is deliberately octave-safe, so a bright, harmonic-rich string does not trick it into reading a note an octave too high. A window of ±5 cents counts as in tune, and the needle turns green the moment you land there.

Every note frequency is derived in twelve-tone equal temperament from a reference A4, which defaults to the modern 440 Hz standard but slides from 415 to 466 Hz — so you can tune to 432 Hz, orchestral 442, or match an out-of-standard piano. Cents are hundredths of a semitone, with 100 cents between adjacent notes, which is why the meter can tell perfectly in tune from a few cents off. If your browser blocks the mic, you can still tune by ear using the built-in reference tone for each string.