Guitar Tuner
A chromatic tuner that listens through your microphone and detects pitch with autocorrelation — six tunings including Drop D and Open G, a manual target mode for badly out-of-tune strings, adjustable A4 calibration, and a tap-to-hear reference tone for every string.
- Pluck one string at a time, not a chord.
- Tune in a quiet room — background noise can throw off detection.
- Let the note ring for a second before reading the meter.
Quick Tips Before You Start Tuning
Features
What Your Browser Is Actually Listening For
Rather than trying to find a peak frequency in a spectrum analysis, this tuner compares the incoming waveform against slightly delayed copies of itself — a technique called autocorrelation. A truly periodic signal, like a plucked open string, lines up almost perfectly with a copy of itself delayed by exactly one wave cycle; that delay is the note's period, and its reciprocal is the frequency. Testing only the delay range that corresponds to real guitar pitches (roughly 55Hz to 1400Hz) instead of scanning everything keeps this fast enough to run smoothly on a phone, and it also avoids the classic "octave error" where a naive detector mistakes a note for one exactly an octave away.
Once the best-matching delay is found, a small correction step interpolates between neighboring samples to estimate the true period more precisely than the raw sample rate alone would allow — this is what pushes the accuracy from "close enough" down to within a cent or two under clean conditions. The same calculation also produces a confidence score, which is what lets the tuner recognize noisy or non-periodic input and simply show nothing rather than a wrong, misleading note.
Auto-Detect vs. Manual Target — and Why Both Exist
Auto-Detect is the default because it's the fastest way to tune a guitar that's already roughly in the right neighborhood — it simply reports whichever chromatic note your string is closest to. The catch is that "closest" only works correctly when a string isn't too far off. A low E string tuned dramatically sharp can genuinely sound closer to F or F# than to E, and Auto-Detect will honestly (and correctly, by its own logic) report that nearer note — which looks confusing if you were expecting it to say "E."
Manual Target sidesteps that entirely: tap the string you're tuning, and the meter locks to exactly that target regardless of how far away the current pitch actually is. It's the mode worth reaching for on a fresh set of strings, after a big tuning change like switching to Drop D, or any time Auto-Detect seems to be naming an unexpected note.
Six Tunings, One Tuner
Standard EADGBE covers most playing, but plenty of styles depend on retuning entirely — Drop D for a heavier low end without changing your fretting hand shapes, Open G and Open D for slide and blues playing where a bare strum already forms a chord, DADGAD for Celtic and fingerstyle arrangements, and Half-Step Down for matching recordings that were tracked slightly flat of standard pitch. Selecting any of these instantly updates both the string labels and the reference tones, so the tap-to-hear pitches are always correct for whichever tuning is active rather than silently assuming standard.
Two Different Tuning Sessions
A beginner picking up a new guitar for the first time starts in Auto-Detect, plucks the low E string, and watches the note name and meter respond in real time — no music theory required, just get the needle into the green zone one string at a time. Setting a recurring Browser Alarm as a daily "check your tuning before practice" nudge is a small habit that keeps a new instrument sounding right session after session.
A gigging guitarist switching to Drop D between songs mid-set instead uses Manual Target on just the low E string, since Auto-Detect briefly reading it as D# or C# while it's sliding down a full step would be more distracting than helpful during a quick retune. Once in tune, keeping tight timing for the next song is a job for the Online Metronome, built with the same sample-accurate Web Audio scheduling this tuner relies on for its own timing precision.
Getting a Clean Reading Every Time
- Rest the guitar body against something stable while tuning. A guitar resting loosely on a knee tends to shift slightly with every pluck, which can subtly affect string tension and sustain mid-reading.
- Mute the strings you're not tuning. Sympathetic ringing from open strings can bleed into the microphone and occasionally confuse detection, especially on acoustic guitars with a resonant body.
- Bring the tuning up from below, not down from above. Tightening into pitch from slightly flat tends to hold more reliably than loosening down from sharp, since string winding mechanics settle differently in each direction.
- Recheck the low strings last. Tuning one string changes the neck tension slightly, which can nudge the others — a final quick pass catches any drift.
- Give a guitar a minute after a temperature change. Coming in from a cold car or a hot rehearsal space, wood and strings are still settling — a tuning locked in immediately often drifts audibly within a few minutes as the instrument equalizes.
New Strings Behave Differently
A freshly strung guitar rarely holds pitch on the first pass no matter how carefully it's tuned, because new strings stretch measurably as they settle into the tuning pegs and against the nut and bridge. Tuning up, playing a few chords, watching the pitch sag, and tuning again — sometimes three or four times over the first day — is normal rather than a sign anything's wrong. Gently stretching each string by hand after restringing (pulling it slightly away from the fretboard and letting it settle back) speeds this process up considerably compared to just waiting it out through playing alone.
Where a Microphone Tuner Reaches Its Limit
A microphone-based tuner is listening to whatever sound actually reaches it, which means anything competing with that sound — amp hiss, a loud room, another instrument playing nearby — competes for the same signal a clip-on tuner sensing string vibration directly through the headstock simply never has to deal with. For tuning on a noisy stage between songs, a clip-on or pedal tuner genuinely has the edge.
It's also built specifically around single, clearly pitched notes rather than chords, percussive playing, or heavily distorted electric tones where the fundamental pitch can get buried under harmonics and noise. For everyday practice-room and bedroom tuning, though — which covers the overwhelming majority of tuning that actually happens — the accuracy here holds up well against dedicated hardware, without needing to own or carry one.