Online Cello Tuner

How to tune your cello, step by step

1. Sit down with the endpin firmly set, and place your phone near the f-holes or the bridge, microphone facing the instrument.
2. Tune the A string (A3, 220.00 Hz) first.
3. Continue with D (D3, 146.83 Hz), G (G2, 98.00 Hz) and C (C2, 65.41 Hz).
4. Use a broad, even bow stroke. On the low strings, wait a second for the note to settle: the stability indicator tells you when the reading can be trusted.
5. Fix small deviations with the fine tuner and large ones with the peg, pushing it inward as you turn.
6. Go around once more to check, and make sure the bridge hasn't tilted toward the fingerboard.

Notes and frequencies

The low C at 65.41 Hz: microphones and low notes

The cello's C string vibrates at 65.41 Hz (C2). That is a low frequency for a phone microphone, whose sensitivity often drops below 80 to 100 Hz. The note can still be detected, because the string also produces much higher overtones, but the reading needs good conditions.

A few habits help: move the phone closer to the instrument (about 30 cm, or 1 foot), cut background noise, play forte with a firm bow stroke rather than a very short pizzicato, and lock the C string so the tuner doesn't confuse the fundamental with its octave. The app's pitch algorithm is built for low notes and stays reliable down to 30.87 Hz; the limit is mostly the microphone.

If the C reading stays unstable, tune the G with the tuner, then tune the C by ear, as a fifth against the G, or with the app's drone.

Fine tuners, pegs and endpin

Most modern cellos have four fine tuners, especially with steel strings. They only cover a small range: if a fine tuner bottoms out, loosen it almost all the way and bring the string back up to pitch with the peg.

Cello pegs are large and hold a lot of tension. Turn them slowly while pressing into the pegbox. The “which way to turn” helper shows a diagram of the pegbox and, by following the note, confirms whether you are going the right way.

Don't forget the endpin: extended to the right length and anchored on a floor where it won't slip, it keeps the instrument steady and stops you from moving the bridge while tuning.

Pure fifths or equal temperament?

Tuned in pure fifths down from the A, the C ends up about 6 cents lower than in equal temperament. In chamber music with strings, this is often desirable for resonance. With a piano, the open C will sound flat: it is better to narrow the fifths slightly, or tune each string directly with the tuner.

The app's drone plays a root, a fifth or a just chord while you play, so you can hear the beats disappear. You can also choose a temperament (Pythagorean, just, Werckmeister III, Vallotti, and more) and its root note.

Reading the note and real-world accuracy

The bow attack is ignored, vibrato is averaged, and the in-tune tolerance defaults to ±3 cents, adjustable from ±1 to ±10 cents. With a phone microphone, real-world accuracy on a cello is about ±2 to 3 cents, a little worse on the C string in a noisy room.

In an orchestra, set the reference A to 442 Hz or calibrate it directly on the oboe's or piano's A. The pitch graph then lets you check, while playing a slow scale, whether your fingers stay in place.