Online Tuner

What a Tuner Actually Measures (Pitch and Cents)

Every musical note corresponds to a frequency measured in hertz (Hz) — the number of times a string or column of air vibrates per second. The A above middle C is, by international standard, 440 Hz. Every other note is a fixed mathematical ratio away from it. When you play a string, the tuner captures a slice of that sound, runs it through an autocorrelation algorithm to find the fundamental frequency, and compares that frequency to the nearest 'correct' note.

The error is shown in cents. A cent is one-hundredth of a semitone — there are 1,200 cents in an octave. This fine resolution is why a tuner can hear a difference your ear might miss. If the meter reads +12 cents, your string is sharp by about an eighth of a semitone; −20 is noticeably flat. A trained listener starts to hear 'out of tune' around ±5 to ±10 cents, which is why the tuner above turns green only when you're within ±5 cents. Aim for the centre, not just 'close.'

Standard Tunings for Each Instrument

• Guitar (standard): E2 A2 D3 G3 B3 E4 — low to high. The classic six-string tuning.
• Bass (4-string): E1 A1 D2 G2 — the same intervals as the bottom four guitar strings, an octave down.
• Ukulele (standard / re-entrant): G4 C4 E4 A4 — note the high G, which gives the uke its bright sound.
• Violin: G3 D4 A4 E5 — tuned in perfect fifths.
• Chromatic mode: detects any note, useful for wind instruments, vocals, sitar, or alternate tunings.

How to Use the Tuner (the Right Way)

Pick your instrument from the selector, press Start, and allow microphone access. Play one string at a time — cleanly, with a firm pluck, in a quiet room. The big letter shows the note the tuner hears; the string dots highlight which string you're closest to; and the needle shows whether you're flat (left) or sharp (right). Turn the tuning peg slowly until the needle sits in the centre and turns green.

Two pro habits. First, always tune up to the note, not down — if you've overshot and the string is sharp, loosen below the target and then tune up to it. This takes the slack out of the gears and the tuning holds far longer. Second, tune in the order the instrument was designed for and re-check the first string at the end; tightening later strings changes the neck tension slightly and can pull earlier strings out. On a guitar, that means a second pass is normal and good practice.

Intonation — Why an In-Tune Guitar Can Still Sound Off

Here's a frustration every guitarist eventually hits: you tune every open string perfectly, then play a chord up the neck and it sounds sour. That's not a tuning problem — it's intonation. Intonation is whether your instrument plays in tune all the way up the fretboard, and it's set by the position of the saddles at the bridge, not the tuning pegs. To check it, tune an open string, then play the harmonic at the 12th fret and the fretted note at the 12th fret; they should read the same on the tuner. If the fretted note is sharp, the string length needs to be increased (move the saddle back); if flat, shortened.

You can diagnose intonation with the tuner above using chromatic mode, but the physical adjustment is a setup job — worth getting done once on any guitar you record with. At 12NOTEZ we set intonation on every guitar before a tracking session, because no amount of careful open-string tuning fixes a chord that's sharp at the 7th fret.

Tuning, Sa, and the Tanpura

In Indian classical music there's no fixed 'A = 440' the way there is in Western music. Instead, the tonic — Sa — is chosen to suit the singer's voice or the lead instrument, and everything is tuned relative to it. A vocalist might set Sa at C# one day and at D another, depending on their range and the time of day. The tanpura is then tuned to drone that Sa (and usually the Pa, the fifth) continuously, giving the performer a constant reference for every other note.

So how does this tuner fit? Use chromatic mode to find and set your Sa precisely — if your harmonium or backing track puts Sa at, say, C#, tune your instrument's reference string to C# and you're locked to the same tonal centre. Then practise with our tanpura tool, which sounds that Sa underneath you so your intonation has something to lean on. The tuner gets you to the exact pitch; the tanpura keeps you there. Western players benefit from this too — playing along to a drone is one of the fastest ways to train your ear to hear when a note is even slightly flat or sharp.

A4 = 440 Hz, and When to Change It

This tuner uses the modern standard of A4 = 440 Hz, which is what virtually all recordings, backing tracks and other instruments use — so unless you have a specific reason, leave it there and you'll be compatible with everyone. You'll occasionally hear about 432 Hz tuning, promoted online as more 'natural'; there's no scientific basis for its claimed benefits, and tuning to 432 just means you'll be slightly flat relative to every other recording and musician you play with. Some orchestras tune to 441–443 Hz for a brighter sound, and older or regional instruments may sit elsewhere, but for practising, recording, and playing with tracks, 440 is the safe, universal choice.

Frequently Asked Questions