Free Online Instrument Tuner

What is an online instrument tuner?

A tuner compares the pitch of a musical note with a reference pitch and shows whether it is flat, sharp, or in tune. Simple Tuners uses your device’s microphone to listen to one note at a time. The display shows the detected note, its octave, its frequency in hertz, and how far it is from the target in cents. You can use it for practice, checking open strings, or checking the intonation of a sustained wind-instrument note.

How to tune with your microphone

1. Choose your instrument or leave the tuner in Chromatic mode. For a string instrument, check that the preset matches the tuning you want.
2. Select Start microphone and allow microphone access in your browser. Place your device where it can hear the instrument clearly.
3. Play one open string or sustain one note. Mute other strings and let the initial attack settle before reading the meter.
4. Check both the note name and octave. Adjust gradually toward 0 cents; the indicator turns green within 10 cents of the target.
5. Repeat for the other strings, then check them again. Select Stop microphone when you finish.

Microphone tuning or reference tones?

Microphone tuning measures the note you play and gives visual feedback. Reference tones let you hear a target pitch and compare it with your instrument by ear. Use the ▶ button beside a target note to play its recording, or hear A4 in Chromatic mode. You can listen to reference tones without granting microphone permission. When checking pitch with the microphone, let the recording finish or use headphones so the tuner hears your instrument clearly.

Which tuning should I choose?

The instrument links open guides with the exact preset notes and frequencies. Standard guitar uses E A D G B E; high-G ukulele uses G C E A; violin and mandolin use G D A E; four-string bass uses E A D G. These note names do not all refer to the same octave. Use the guide for your instrument to check the full targets, and choose Chromatic for alternate tunings. Wind-instrument readings use sounding concert pitch rather than transposed written notes.

Chromatic tuning in your browser

Chromatic mode follows the nearest note in the twelve-note equal-tempered scale. Instrument presets narrow the targets to their listed strings or reference notes.

What do flat, sharp, and cents mean?

Flat means your pitch is below the target; sharp means it is above it. A cent is one hundredth of a semitone. Move toward 0 cents using small adjustments. For strings, tighten to raise pitch and loosen to lower it.

Can I change the reference pitch?

Reference A4 defaults to 440 Hz and accepts 400–480 Hz. Match your ensemble’s reference before tuning. The selected preset keeps its note names while its target frequencies adjust.

Why is the tuner not picking up my instrument?

Check that your browser has microphone permission and that your device has selected the right microphone. If you denied access earlier, reopen the site’s microphone settings and allow it, then try again. Use a quiet room, move closer to the microphone, and play one steady note. Chords, background music, and ringing strings can produce an unclear reading. If you see the right note in the wrong octave, try a gentler note and check for harmonics before changing string tension.

Can I use this tuner on a phone or computer?

Use a browser that supports microphone access and JavaScript, with a working built-in or external microphone. No app download or account is required. Microphone audio is processed on your device and is not uploaded. You can stop access with Stop microphone or revoke permission in your browser. Reference recordings are available even if you prefer to keep the microphone off.