How to Use This Tuner
Click Enable microphone and allow access when your browser asks. Play one string at a time — open, not fretted — and let it ring. The big letter shows the nearest note, the needle shows how many cents sharp or flat you are (100 cents = one semitone), and the badge turns solid when you are within ±5 cents. Tune up toward the pitch, not down: if you are sharp, loosen below the note first, then tighten up to it. Strings hold tune better when the final adjustment tightens the tuning peg, because it seats the string firmly against the nut and post.
For string-by-string mode, tap a string button (low E through high E) and the tuner tells you which string to play and its exact target frequency. Work from low E to high E, then go around once more — tightening one string pulls the neck slightly and detunes the others, so the second pass is where stability comes from. New strings need three or four full passes plus some stretching before they settle.
Understanding the Needle
The gauge reads in cents, the standard unit of tuning error. Zero means perfect; negative is flat (too low), positive is sharp (too high). A few cents of error is inaudible to most ears in isolation — ±5 cents is the practical "in tune" zone this tuner uses. But cents add up across strings: if every string is 8 cents sharp, chords sound noticeably tense, which is why the badge only lights up inside the ±5 window.
Watch the needle's behavior, not just its position. A healthy plucked string starts slightly sharp (the attack stretches it) and settles toward its true pitch within a second — tune to the settled reading, not the attack. If the needle jumps wildly, you are probably hearing room noise, a second string ringing, or fret buzz; mute the other strings with your picking hand and play the string cleanly near the 12th fret for the purest tone.
The Six Strings, in Order
Standard tuning, low to high: E2 (82.4 Hz), A2 (110 Hz), D3 (146.8 Hz), G3 (196 Hz), B3 (246.9 Hz), E4 (329.6 Hz) — memorized by generations of players as "Eddie Ate Dynamite, Good Bye Eddie." The interval pattern is fourths between every pair of adjacent strings except G to B, which is a major third; that one exception is what makes chord shapes interesting and tuning by ear tricky.
Alternate tunings in the selector change the targets: Drop D lowers only the low E to D2 (73.4 Hz) for heavier riffs with easy one-finger power chords; half-step down drops every string one semitone (Eb standard — a favorite of blues and rock players for a slightly slinkier feel and easier vocals); Open G (D2–G2–D3–G3–B3–D4) turns the open strings into a G major chord, the classic slide-guitar and Stones tuning. When switching tunings, always go string by string and re-check, because changing one string's tension shifts the neck and moves the rest.
Tuning by Ear: The 5th-Fret Method
Electronic tuners are precise, but every guitarist should know the traditional method for when no tuner is available. Get one reference string in tune (low E from a piano, a tuning fork, or this page), then: fret the low E at the 5th fret — that pitch is A, matching the open A string. Fret the A at the 5th fret to tune the D string; the D at the 5th fret to tune G. The exception: fret the G at the 4th fret to match the open B. Then fret the B at the 5th fret to tune the high E. Check by playing octaves and harmonics — the 5th-fret harmonic of one string should match the 7th-fret harmonic of the string above it, and beats between them reveal tiny errors your eye might miss.
Why Guitars Go Out of Tune
Strings go flat far more often than sharp, and the causes are physical. New strings stretch for days — pre-stretch each one by gently pulling it away from the fretboard and re-tuning, repeating until it holds. Temperature and humidity move wood: heat and dryness shrink the neck and drop pitch, which is why guitars detune in hot cars and cold venues. Playing hard — especially bending — pulls strings sharp or flat at the nut if the slots bind; a touch of graphite (pencil lead) in the nut slots helps strings return to pitch.
The mechanical suspects: slipping tuning posts (make sure the string wraps downward on the post, 2–3 neat winds), a nut cut too tight, old strings (change them every 1–3 months of regular playing — dead strings won't intonate no matter how you tune), and a floating tremolo, which detunes everything when you touch one string. If one string chronically misbehaves, the hardware — not your technique — is usually guilty.
Intonation: When Open Strings Lie
A guitar can be perfectly in tune open and still sound wrong fretted — that is an intonation problem, not a tuning problem. Check it: play the 12th-fret harmonic, then fret the 12th fret normally. They should match. If the fretted note is sharp, the string is too short — move the saddle back; if flat, move it forward. Adjust in small increments and re-tune the open string after every move, since saddle position and open tuning interact.
Intonation drifts as strings age and with big temperature swings, so check it whenever you change string gauge or notice chords sounding sour up the neck while open chords sound fine. It is a five-minute adjustment with a screwdriver that makes the whole fretboard sound more expensive than it is.
How This Tuner Hears Pitch
Under the hood, this page runs autocorrelation on your microphone signal: it slides the waveform against itself at different time lags and finds the lag where the signal best matches itself — that lag is the wave's period, and frequency is its reciprocal. A parabolic refinement around the best lag gives sub-sample accuracy, and the frequency is converted to the nearest musical note with a cents deviation. It is the same core technique used in many hardware tuners, running entirely in your browser — no audio ever leaves your device.
For best results, use a quiet room, hold the guitar near the microphone, and pluck with moderate force — very hard plucks add inharmonic overtones that can confuse any pitch detector, and very soft plucks drown in noise. Laptop microphones work fine; phone mics work even better.
Tuning Tips for Beginners
Tune every time you pick up the guitar — it takes 60 seconds and it is the single highest-leverage habit in musicianship, because you cannot train your ear on an out-of-tune instrument. Always tune up to the note, stretch new strings, and re-check after a few minutes of playing. Learn what "in tune" sounds like by strumming a chord slowly and listening for beats — the slow wobble between two nearly-matching pitches — and practice eliminating them. Within weeks, your ear will start catching drift before any tuner does, and that is when tuning stops being a chore and starts being musicianship.
Beyond Guitar: Bass, Ukulele, and Everything Else
This is a chromatic tuner, which means it hears any note — not just guitar strings. Bass players: your open strings are E1 (41.2 Hz), A1 (55 Hz), D2 (73.4 Hz), G2 (98 Hz), all comfortably inside the detection range; pluck gently near the neck for the cleanest reading, since hard bass attacks confuse pitch detectors. Ukulele standard tuning is G4–C4–E4–A4 (392, 261.6, 329.6, 440 Hz) — the tuner reads them all, though the reentrant high G can surprise players expecting low-to-high order. Violin, viola, and cello work too (G3–D4–A4–E5 for violin), as does any wind instrument for checking intonation against a tuner. The ±5-cent "in tune" badge is calibrated for fretted instruments; orchestral players often want tighter (±2–3 cents), so watch the raw cents number rather than the badge. Whatever the instrument, the technique is identical: quiet room, clean attack, let the note settle, tune up to the pitch. The physics of vibrating strings does not care what shape the wood is.