Chromatic online tuner: how to read it properly

Tuning is one of the few things in music with an objective answer, and yet plenty of people do it halfway: they reach the green zone, call it done and never ask why the chord still sounds off. The needle gives you a number; understanding what it means is what stops you repeating the whole thing every ten minutes.

This tuner listens through your microphone and works with any instrument, because it's chromatic: it doesn't assume you're tuning a guitar. Green below 5 cents, amber up to 15 and red beyond — and that colour code is more useful than the exact number when both your hands are busy.

Two habits that save time

First: always arrive at the note from below. If you overshoot, drop under it and come back up. Tuner and string have slack, and a note reached from above drifts on its own as soon as you play for a while. Second: do a second pass over every string. Tensioning one slightly changes the neck's tension and the others move, so the first pass is never the real one — especially with new strings, which keep stretching for days.

Tuning a bass: the awkward case

Bass is where most tuners fall over, and not arbitrarily. Its lowest string vibrates at around 41 Hz on a four-string and 31 Hz if you have a low B on a five, frequencies so low that many phone tuners don't even try and others latch onto the first harmonic and show you the octave above. This one reads from 20 Hz up, so it covers both.

If the reading still jumps an octave, it's nearly always your plucking hand. A hard attack near the bridge fires up the harmonics and leaves the fundamental sitting under them; pluck softly, with the pad of your finger, nearer the end of the fingerboard, and let the string ring on its own for a second before reading. The usual tunings: E A D G on a four-string, with a low B underneath on a five.

Tuning is measuring; your ear is another matter

A tuner tells you whether you're on the note; it doesn't teach you to hear it. If you want to recognise pitch without looking at the screen, that trains separately — and it's one of the skills in ear training. For a reference to compare against while tuning by ear, there's the online piano, tuned to the same 440 Hz reference.

Frequently asked questions

Do I need to install an app?
No. It runs in the browser and only needs microphone permission. That permission is requested when you hit start and you can revoke it any time; the audio never leaves your device.
Does it work for any instrument?
Yes, it's a chromatic tuner: it recognises all twelve notes, so it works for guitar, bass, ukulele, violin, wind instruments and voice. It isn't limited to a guitar's six strings the way fixed-instrument tuners are.
What are the cents it shows?
A cent is one hundredth of a semitone, and it's the unit for how far off the note you are. Below about 5 cents counts as in tune and the ear can't tell. From 15 it's noticeable, and past 20 or 25 it sounds wrong inside a chord.
What reference pitch does it use?
A4 = 440 Hz, the international standard and the same one a tuned piano and every other tuner use. If you play with a band, everyone should be on that reference.
The needle keeps jumping around — what do I do?
That's usually background noise or a note dying away. Play the open string firmly, let it ring on its own and read the needle in the first second, when the pitch is most stable. If there's talking or music nearby, move the instrument closer to the mic.
Can I tune a bass with it?
Yes. It reads from 20 Hz up, so it covers the low E of a four-string bass (41 Hz) and the low B of a five-string (31 Hz), which is where a lot of phone tuners give up. If the reading jumps to the octave above, pluck softer and with the pad of your finger, nearer the end of the fingerboard than the bridge: that way the fundamental outweighs the harmonics.
What's standard tuning for my instrument?
Guitar: E A D G B E from the sixth string to the first. Four-string bass: E A D G; a five-string adds a low B underneath (B E A D G). Soprano ukulele: G C E A. Violin: G D A E.