How to Tune a Bass With an Online Bass Tuner
To tune a bass with an online bass tuner, open the Guitar Tuner, click Bass, press Start tuner, and pluck one string at a time, turning its peg until the note turns green. Go from the thickest string to the thinnest (E, A, D, G), then go round once more. It takes a couple of minutes.
The steps are the same as for a six-string, which How to Tune a Guitar With an Online Tuner covers in full. This guide covers what's different on bass: lower notes, a microphone that struggles to hear them, and a harmonics trick that gets around the problem.
What you'll need
- A 4-string bass. An acoustic bass is easiest. An unplugged electric bass is quiet, so hold the body close to the mic, or play through an amp at a modest volume.
- A phone, tablet, or laptop with a microphone.
- A quiet room.
There is nothing to install and no account. The first time you press Start tuner, your browser asks for permission to use the microphone. The tuner analyses the sound live in the browser, so your audio never leaves your device. Nothing is recorded, stored, or uploaded.
Standard bass tuning: E A D G
A 4-string bass is tuned E, A, D, G from the thickest string to the thinnest. These are the same notes as a guitar's four lowest strings, one octave lower.
| String | Note | Frequency | Same note on guitar |
|---|---|---|---|
| 4th (thickest) | E1 | 41.20 Hz | E2, 82.41 Hz |
| 3rd | A1 | 55.00 Hz | A2, 110.00 Hz |
| 2nd | D2 | 73.42 Hz | D3, 146.83 Hz |
| 1st (thinnest) | G2 | 98.00 Hz | G3, 196.00 Hz |
The frequencies assume A4 = 440 Hz. In Bass mode, the tool's string buttons show E1, A1, D2 and G2 with their frequencies rounded to one decimal place: 41.2, 55.0, 73.4 and 98.0.
How to use a tuner for bass guitar, string by string
- Click "Bass". Guitar is selected by default, and in that mode the tuner is listening for guitar strings. Bass mode only knows the four notes above.
- Leave "A4 =" at 440 Hz unless you're matching an instrument tuned to something else.
- Press the amber "Start tuner" button and allow the microphone. The hint changes to "Listening… pluck a single string and let it ring".
- Pluck the E string and let it ring. The readout shows the note it's closest to, with a line under it such as "41.0 Hz · -9 cents".
- Follow the hint. "Too low — tune up" means tighten. "Too high — tune down" means loosen. If a string is sharp, loosen it below the note and come back up to it, so the tuning machine holds its position. The hub guide explains why you tune up to pitch.
- Stop when it goes green. The note and needle turn green and the hint reads "In tune" once you're within 5 cents. The matching button in the row labelled "Strings — tap to hear the reference note" lights up too, so you can confirm the tuner heard the string you meant.
- Repeat for A, D and G, then do a second pass. Bass strings are heavy, and retensioning one shifts the load on the neck enough to nudge the others.
- Press "Stop tuner" to release the microphone.
A cent is one hundredth of a semitone. The guide to semitones and cents has more, but on a tuner all you need is: needle left is flat, needle right is sharp, centre and green is done.
Why phone and laptop mics struggle with the low E
The built-in mic on a phone or laptop is designed mainly for speech, and many pick up comparatively little at 41 Hz, which sits in the lowest stretch of the audible frequency range. An open E string still sounds full because of its overtones, the higher partials at two, three and four times the fundamental, but the fundamental itself reaches the mic weakly.
The tuner handles this by measuring pitch from the repeating period of the waveform (autocorrelation), not by picking the loudest frequency. A low E whose overtones are louder than its fundamental still repeats 41 times a second, so the tuner can still identify it. The detector goes down to about 35 Hz, which covers a 4-string bass's low E, and it checks against reading a note one octave too low. What it can't fix is a signal that's too weak to trust. When that happens the display stays on "Listening…".
To give the mic more to work with:
- Get the bass close to the mic. A few centimetres from an acoustic's soundhole, or the body of an unplugged electric bass held right by the phone.
- Pluck firmly with a finger, not a slap or a pop.
- Mute the strings you aren't tuning with your fretting hand.
- Let the note ring rather than plucking again straight away.
- If you have an amp, play through its speaker at a moderate volume. An online electric bass tuner gets a far stronger signal from an amp than from a quiet unplugged body.
The 12th-fret harmonic trick
If the low E won't register, tune its harmonic instead. Rest a fingertip lightly on the string directly above the 12th fret wire, without pressing it down. Pluck near the bridge and lift your finger. You'll hear a bell-like note one octave above the open string. Yamaha's guide to bass guitar harmonics has more on the technique.
The harmonic is easier for a phone mic to hear. It's twice the frequency, so the E string's harmonic is E2 at 82.41 Hz, and it rings clearly for a long time.
Switch to Chromatic before tuning harmonics. In Bass mode the tuner snaps every reading to the nearest of E1, A1, D2 and G2. A harmonic is an octave up, so it snaps to the wrong string. The E string's E2 harmonic, for example, reads as D2 and pinned far too high. Chromatic mode shows the note actually being played:
| String | 12th-fret harmonic should read |
|---|---|
| E | E2 (82.41 Hz) |
| A | A2 (110.00 Hz) |
| D | D3 (146.83 Hz) |
| G | G3 (196.00 Hz) |
Tune each harmonic until it is centred within 5 cents. The cents offset is the same an octave up, so an in-tune harmonic means an in-tune open string.
The same harmonic, compared with the fretted note at the 12th fret, is also the standard intonation check; the guitar guide explains it.
5-string basses and other tunings
5-string bass (low B). The open low B is B0, about 30.87 Hz. That's below the tuner's roughly 35 Hz detection floor, and the Bass preset only has four strings. Tune the B string by its 12th-fret harmonic in Chromatic mode. It should read B1, about 61.74 Hz. Tune the other four strings as normal.
Drop D. Lower the E string a whole step to D1 (36.71 Hz). That's close to the detection floor, and in Bass mode it would snap to E1 and read as far too low. Use Chromatic and tune the 12th-fret harmonic to D2.
Half-step down (E♭ A♭ D♭ G♭). Use Chromatic. The tool names notes with sharps, so the targets show as D♯1, G♯1, C♯2 and F♯2, the same pitches under their sharp names. The low D♯1 is near the floor too, so the harmonic method helps on that string.
Tuning by ear with the reference tones
In Bass mode, tap E1, A1, D2 or G2 to hear that note for about three seconds. Tap again to stop it. This works without the microphone.
Laptop and phone speakers barely reproduce 41 Hz, though. The tone is a triangle wave, so on small speakers you mostly hear its upper harmonics rather than the fundamental. Use headphones or decent speakers if you want to hear the low E properly.
Without any tuner, the 5th-fret method tunes the bass to itself:
- E string, fret 5 = open A
- A string, fret 5 = open D
- D string, fret 5 = open G
This only tunes the strings relative to each other. If the E is flat to begin with, the whole bass ends up flat.
Troubleshooting
It stays on "Listening…"
The signal is too quiet. Move closer, pluck harder, or try the 12th-fret harmonic. If nothing registers at all, check that your microphone isn't muted or run the Mic Test to see whether any input is reaching the browser.
It shows the wrong string, or the needle is pinned
In Bass mode the tuner snaps to the nearest open string. A very slack string can land closer to its neighbour than to its own note. An A string tuned down a long way, for example, can read as E1 with "Far too high — loosen the string", the opposite of what it needs. Switch to Chromatic, bring the string to the right note name, then go back to Bass for the fine work.
The reading jumps around
Mute the other strings, pluck more softly over the end of the neck, and check for fret buzz. A buzzing string adds noise the tuner has to fight through.
It goes flat again soon after tuning
New bass strings are heavy and take a while to stretch and settle, so expect to retune often for the first few sessions. The guitar guide covers the other causes in its troubleshooting section.
Online bass tuner or clip-on electronic tuner?
At home, an online tuner is plenty. On a loud stage, a clip-on bass guitar electronic tuner is the better tool: it senses vibration through the headstock, so the noise in the room doesn't reach it.
Related
If you're learning a song, How to Extract a Bassline From a Song shows how to isolate the bass part with the Stem Splitter. To practise it at a comfortable tempo, see How to Slow Down Music to Practice an Instrument, and keep time with the Metronome.
The "A4 =" field accepts 415 to 466 Hz. What Is Concert Pitch? explains why 440 is the default and when to change it. More walkthroughs are in the audio how-to guides.
Frequently asked questions
What notes is a bass tuned to?
A standard 4-string bass is tuned E, A, D, G from the thickest string to the thinnest. With A4 at 440 Hz, those notes are E1 at 41.20 Hz, A1 at 55.00 Hz, D2 at 73.42 Hz and G2 at 98.00 Hz. They're the same notes as a guitar's four lowest strings, one octave lower. A 5-string bass adds a low B (B0, about 30.87 Hz) below the E.
Can I use a guitar tuner for bass?
Yes, if it can detect notes low enough. Bass notes are an octave below a guitar's, and a tuner built only for guitar may not hear the low E at 41 Hz or may snap it to the wrong string. The Vocal Cut Guitar Tuner works as a bass and guitar tuner: click Bass and it tunes to E1, A1, D2 and G2, listening down to about 35 Hz.
Why won't my tuner pick up my low E?
Phone and laptop microphones are designed mainly for speech and often capture little energy at 41 Hz, so the low E's fundamental reaches them weakly. Hold the bass closer, pluck firmly, mute the other strings and let the note ring. If it still won't register, play the 12th-fret harmonic, switch the tuner to Chromatic, and tune it to E2. That tunes the open string too.
How do I tune a 5-string bass online?
Tune the E, A, D and G strings in Bass mode as usual. The low B (about 30.87 Hz) is below the tuner's detection range and isn't in the Bass preset, so switch to Chromatic and play the B string's 12th-fret harmonic instead. Tune that harmonic to B1, about 61.74 Hz, and the open B will be in tune.
Are online bass tuners accurate?
For bass, the weak point is the microphone rather than the maths: low notes reach a phone or laptop mic weakly, and the mic hears the room too. This tuner measures pitch on your device and shows it to the nearest cent, finer than most people can hear. In a quiet room with the bass close to the mic, it works well. On a loud stage, a clip-on tuner is more reliable.