Bass tuner
E, A, D and G on a four-string bass, with the sound kept on your device.
- Nothing is uploaded
- Works offline after first visit
- Open source
- Free, no account. The microphone is on only until you press Stop
Tune a four-string bass to E, A, D and G with your microphone, or press a string button to hear each note and tune by ear. The tuner shows the string it hears and a needle for sharp or flat. It is free, and the sound from your microphone is not uploaded: everything runs in your browser on your device.
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Play one string or note
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Done
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A four-string bass is tuned E1, A1, D2 and G2, from the thickest string to the thinnest. Those are the note names of the guitar’s lowest four strings, one octave down, so the bass’s low E vibrates at 41.20 Hz against the guitar’s 82.41 Hz. Press Start the tuner, play one open string, and the tuner lights the string it is closest to and shows how far off it is.
A worked example: you play the open D, the second string, and the tuner shows D with the needle to the right and “9 cents sharp: tune down”. Ease the peg down until the needle sits in the shaded middle and the D button fills in. Low notes take longer to settle on screen than a guitar’s: pluck once, let the string ring, and give the needle a second.
Once the E is right you can check the others against it with the fifth fret: the fifth fret of the E string sounds the open A, the fifth fret of the A sounds the D, and the fifth fret of the D sounds the G. The method is the one in how to tune a guitar, an octave lower.
The four open strings
The frequencies use the usual reference, A4 = 440 Hz, in equal temperament. They are the same numbers the page shows as a tooltip on each string button.
- 4th string, E: E1, 41.20 Hz
- 3rd string, A: A1, 55.00 Hz
- 2nd string, D: D2, 73.42 Hz
- 1st string, G: G2, 98.00 Hz
What this page does not do
- There is no B string. The list is for four-string basses; the low B of a five-string (B0, 30.87 Hz) is not in it.
- There is no input selector or cable input. The page uses the microphone your browser picks, so an unplugged electric bass, which is quiet, needs an amp with the device held near it, or the device held close to the strings.
- It names the open string nearest in pitch. A string more than about two and a half semitones flat can be taken for its lower neighbour, so bring a very slack string close by ear before you read the needle.
- It does not set intonation or string height. If the open strings are in tune but notes up the neck are not, that is a set-up job.
How it works
- Press Start the tuner and allow the microphone. Bass, 4 strings is already chosen.
- Play one open string and let it ring for a moment. The nearest of E, A, D and G lights up and the needle shows sharp or flat.
- Turn the peg until it says In tune, then tune the next string, E up to G.
In your browser, not on a server
Your browser opens the microphone (getUserMedia) with its noise suppression and automatic gain turned off, and the Web Audio API hands this page about 85 ms of sound twenty times a second. Each slice is compared with delayed copies of itself (the McLeod pitch method) to find the period of the note, which gives its frequency to a fraction of a hertz; the reading is then dropped. The string buttons play a tone from a Web Audio oscillator.
Compared with upload-based tools: Tuner apps ask for an install and access to much more than the microphone, and many tuner websites are buried in ads and trackers. Here the sound goes from your microphone to this tab and nowhere else, and nothing is kept.
Verify it yourself. Give the page a short while after one visit to save itself for offline use, then turn off Wi-Fi or switch to airplane mode and run the tool again. Or open your browser's developer tools (F12, or Cmd-Option-I on a Mac), pick the Network tab, and watch it while you convert. The panel above does the same count for you.
Questions
Can I tune a five-string bass?
The E, A, D and G of a five-string bass are the same notes and tune here. The low B is B0 at 30.87 Hz, which is not in the list and sits just above the lowest pitch this tuner listens for, about 30 Hz. In our tests with recorded bass notes it read a note at that pitch, but a phone or laptop microphone picks up very little that low, so it may not settle on yours. Choose Chromatic, play the B and read the note name, or tune the B so that its fifth fret matches the open E.
Why does the guitar setting not work for my bass?
The guitar list starts at E2, 82.41 Hz, an octave above the bass’s low E. Played against that list, your low E reads as a very long way flat, with the needle pinned at the left edge. Choose Bass, 4 strings and each string is aimed at its own note.
How do I tune to drop D?
Choose Chromatic, play the low string and lower it a whole step, through D♯, until the big letter says D: that is D1 at 36.71 Hz. The other three strings stay as they are. The Chromatic setting has no string buttons, so there is no reference tone for the D.
The E button is hard to hear on my phone or laptop. Is it working?
Probably. The E is 41.20 Hz and small speakers play very little that low; what you hear is mostly the overtones of the tone. Headphones or a larger speaker show the note much better, and the overtones are still enough to tune against by ear.
Is the sound from my microphone recorded or uploaded?
No. The pitch is measured by code running in this tab, about twenty times a second, and no sound is recorded or stored: only the last few pitch readings are held in memory while the tuner listens. Press Stop using the microphone to turn it off. Like any website, the host sees your connection’s IP address when the page loads, and the site counts visits with anonymous usage events that never include sound; the privacy page lists them field by field.
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