# Free cello tuner, C2, G2, D3 and A3 reference tones

The cello’s open strings are C2, G2, D3 and A3, from lowest to highest, separated by perfect fifths. With A4 = 440 Hz as the reference, the cello’s A3 sounds at 220 Hz. Use the free reference tones or microphone meter below to check each open string; no signup is required.

[Open the free cello tuner](/tools/tuner/cello)

Reference tones need no microphone permission. Microphone analysis begins only after you choose Start tuning and grant access. Audio is analysed on your device, not recorded or uploaded. Stop the tuner when finished.

## Open strings, low to high

A440 describes A4, not the open cello A. Your A3 target is 220 Hz at that setting, 221 Hz at A442, and 207.5 Hz at A415. Do not tighten a cello A string toward 440 Hz.

| Sounding note | String number | Frequency at A440 |
| --- | --- | --- |
| C2 | 4 | 65.41 Hz |
| G2 | 3 | 98.00 Hz |
| D3 | 2 | 146.83 Hz |
| A3 | 1 | 220.00 Hz |

Frequencies below use equal temperament with A4 = 440 Hz and are rounded to two decimal places. Advanced settings shift all reference tones to A442 or A415. Follow your ensemble’s agreed pitch; these readings do not replace listening or instrument-specific advice.

## Tune step by step

1. **Set the reference and find A3.** Keep Cello selected. Listen to the A-string tone; at the default reference it is 220 Hz. Let the tone finish, then bow the open A with the left hand clear.

2. **Check the note before the cents.** Start the microphone meter if desired. Confirm A3, then read the sharp or flat indication. A reading of A4 can be an overtone; do not chase a different octave by tightening the string.

3. **Work downward through D, G and C.** Compare D3, G2 and C2 in turn. Use a steady stroke and give each low note time to settle. Use a fine tuner for small changes where fitted; ask a teacher for help with pegs or a string far from pitch.

4. **Repeat the circuit.** Recheck A3 after the other strings, then sound a quiet open-string sequence. If a fine tuner is at its limit or a peg slips, stop and seek help rather than forcing the mechanism.

## Why A440 produces a 220 Hz cello tone

Pitch standards name the A above middle C. The cello’s open A is one octave below that reference, so its frequency is half as large. The note-name and octave readout is therefore just as important as the needle: an A in the wrong octave is not a tuning target.

The same octave distinction separates cello and viola. Both have C–G–D–A strings, but a viola preset plays each reference an octave above the cello. This page starts on the cello setting so the buttons correspond to the strings in your hands.

## Troubleshooting C and G without chasing the display

A low cello tone contains higher harmonics as well as its fundamental. Background music, another open string vibrating, or a strong bow attack can also confuse a microphone reading. Silence other sound sources, sound one open string, and compare the audible reference before interpreting an unexpected octave.

A phone speaker may make the lowest reference sound quiet. Keep playback at a comfortable level; headphones can make the reference easier to hear, but remove them if you need to compare the room sound naturally. Neither a stable meter nor green colour certifies bow technique or the intonation of a whole phrase.

## Questions about tuning

### Should the cello A string be 220 Hz or 440 Hz?

At the standard A440 reference, the open cello A is A3 at 220 Hz. The setting refers to A4, one octave higher. Do not tune the cello A string an octave above its intended pitch.

### What is the lowest cello string?

The lowest standard cello string is C2, approximately 65.41 Hz at A440. Above it are G2, D3 and A3. These are sounding pitches, not a transposed notation.

### Can I tune a cello without fine tuners?

The pitch can be adjusted with the pegs, but a beginner should learn that movement with a teacher. This page cannot assess peg fit, string tension or bridge position. Never force a stiff peg or keep tightening when the octave is uncertain.

### Does the cello tuner save recordings?

No. Microphone pitch analysis runs on the device; the tuner does not record, store or upload the audio. Reference tones work without opening the microphone.

## Keep practising

[Cello fingering chart](/charts/cello)

[Cello lessons](/learn/cello)

[Complete string tuning guide](/guides/how-to-tune-a-string-instrument)

[Free metronome](/tools/metronome)

## Reference sources

- [Yamaha: the cello and its tuning](https://www.yamaha.com/en/musical_instrument_guide/violin/structure/structure005.html)

Updated 2026-08-31.

Canonical source: https://arcosounds.com/tools/tuner/cello