# Free viola tuner, C, G, D and A open strings

A viola is tuned C3, G3, D4 and A4 from low to high, in perfect fifths. Its A string matches a violin’s A4, while its C string is an octave above a cello’s C2. Play the four reference tones or use the free microphone tuner below, without signing up.

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

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

The viola A string is A4, 440 Hz at A440. Its lowest string is C3, approximately 130.81 Hz. A cello uses the same letter names one octave lower; selecting the correct instrument avoids that mismatch.

| Sounding note | String number | Frequency at A440 |
| --- | --- | --- |
| C3 | 4 | 130.81 Hz |
| G3 | 3 | 196.00 Hz |
| D4 | 2 | 293.66 Hz |
| A4 | 1 | 440.00 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. **Match the viola A4.** With Viola selected, listen to the A reference. Use A440 unless your ensemble has agreed otherwise. Keep the left hand off the string so you hear the open A rather than a stopped note.

2. **Move through D and G.** Let each reference tone finish before listening with the microphone. Bow a single string steadily and check D4, then G3. Minus cents means flat and plus cents means sharp relative to the selected reference.

3. **Give the low C room to speak.** Sound C3 with an even, unforced stroke, keeping clear of the neighbouring G. Wait for a stable pitch rather than adjusting in response to the noisy start of a bow stroke.

4. **Return to A and compare fifths.** Recheck A after small adjustments to the other strings. Listen to C–G, G–D and D–A if you can sound each pair cleanly. Ask for help with pegs rather than forcing them.

## Coming to viola from violin

Three strings retain the familiar violin pitches: G3, D4 and A4. The change is at the ends of the range: viola adds C3 below G and has no violin E5 string. Do not select a violin preset simply because the A reference sounds familiar; it would leave the low C without the correct open-string guide.

The viola normally reads alto clef, but a clef changes how notes are written, not the frequency of the open string. The tuner displays sounding note names. You do not need to transpose a displayed C3 before comparing it with your viola’s C string.

## When the low C reading will not settle

First check that the bow is sounding just the C string and that no reference tone is still playing through the speaker. A quiet room makes the instrument easier to isolate. If the microphone hears a strong overtone, it may show a C in a higher octave; compare by ear before deciding the string needs a large adjustment.

Different viola sizes still use these standard pitches. String choice and instrument setup affect the feel under the bow, but changing the reference from 440 to 442 is not a cure for a slow or scratchy response. Use small pitch corrections, and discuss a persistent response problem with your teacher.

## Questions about tuning

### Are viola and cello strings tuned to the same notes?

They share the letter names C, G, D and A, but the viola sounds one octave higher: C3–G3–D4–A4 versus cello C2–G2–D3–A3.

### Does alto clef change how I use the viola tuner?

No. The meter names the sounding pitch directly. Alto clef places middle C on the middle staff line, but tuning the open strings does not require reading a staff or transposing.

### What frequency is the viola C string?

C3 is approximately 130.81 Hz with A4 set to 440 Hz in equal temperament. Changing the reference to 442 or 415 shifts all four reference tones together.

### Can I use the viola reference tones with microphone permission denied?

Yes. The open-string audio buttons do not require microphone permission or an account. The meter only listens after you choose Start tuning and allow access.

## Keep practising

[Viola fingering chart](/charts/viola)

[Viola lessons](/learn/viola)

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

[Free metronome](/tools/metronome)

## Reference sources

- [Yamaha: violin and viola owner’s manual](https://usa.yamaha.com/files/download/other_assets/0/313360/02_violin_E_0702.pdf)

Updated 2026-08-31.

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