Online cello tuner

Cello string notes

Frequencies are calculated with the reference A at 440 Hz. If your group tunes to a different reference, such as 442 Hz, adjust it with the − and + buttons next to “A = 440 Hz” and the tuner shifts every note.

An octave below the viola

The cello's strings are C2, G2, D3 and A3: the same notes as the viola, an octave lower. Its A vibrates at 220 Hz, exactly half the 440 Hz reference A, so the tuner recognizes it as an A even though it sounds lower. 1/4, 1/2, 3/4 and 4/4 cellos all tune to the same notes.

Tuning with harmonics

Harmonics sound steadier than the open string and are easy to compare. Touch the string lightly, without pressing down, exactly at its midpoint: it sounds an octave higher, and the tuner reads it as the same string.

To compare two neighboring strings, play the harmonic at one third of the length of the lower string and the one at the midpoint of the higher string: they should sound the same. For example, the one-third harmonic on the D string gives an A4, the same as the midpoint harmonic on the A string. This gives you pure fifths, slightly wider than the piano's; if you're going to play with piano, finish adjusting each string with the tuner.

Pegs and fine tuners on the cello

Many student cellos come with fine tuners on all four strings; others only on the A string. Use them for fine adjustments and save the peg for big changes, turning it while gently pushing it in so it doesn't slip back. If a fine tuner runs out of thread, loosen it to the middle of its range and bring the string back in tune with the peg. And if the bridge starts leaning toward the fingerboard after several tunings, ask your teacher to check it before it warps.

How to tune your cello with this tuner

1. Tap Enable microphone and accept the browser's permission request. The sound is analyzed on your device: it isn't recorded or sent anywhere.
2. Leave the tuner on Auto so it recognizes which string you're playing, or tap a note to lock it (tap it again to go back to Auto).
3. Play a single open string with medium force and let it ring.
4. If the needle is to the left, the note is flat: tune up. If it's to the right, tune down. Anywhere between −5 and +5 cents counts as in tune.
5. Once a string stays in tune for a moment, its button gets a green check mark. Keep going until every string has one.
6. Use the speaker icon under each note to hear the reference and train your ear.
7. Go over every string again at the end: the tension of some strings shifts the others slightly.

Tips for tuning your cello

• The cello's low notes need a long, steady sound: use full bows when tuning.
• Tune the A first with its fine tuner, then work your way down string by string, checking the fifths.
• If you need to turn a peg, loosen the string a little before bringing it up, and don't overshoot the note.
• If the microphone doesn't pick up the C string well, play its harmonic at the midpoint of the string.

Common tuning problems

• The needle jumps between notes: play a single string, a little more softly, and wait for the sound to settle. The first instant of every note always sounds slightly sharp.
• It doesn't pick up the low strings: phone microphones struggle with low frequencies. Hold your phone closer to the instrument or play the harmonic at the middle of the string (12th fret): the tuner recognizes it as the same string and tells you it sounds an octave higher.
• The open strings are in tune, but what you play sounds off: check that no string is in the wrong octave and that your strings aren't old. If it still sounds wrong, ask your teacher or a luthier to check the instrument's intonation.
• It goes out of tune right away: new strings keep stretching for several days, and changes in temperature and humidity shift the tuning. Tune in the same place where you're going to play.
• The browser doesn't ask for the microphone: check the site permissions in your browser settings and make sure no other app is using the microphone.

Frequently asked questions