How to use this tuner

1. Pick your tuning. Standard 4-string EADG covers most working basses. Pick Drop D if you're playing rock or metal with the low E tuned down a whole step. Pick 5-string if you have a low B; 6-string if you also have a high C above the G.

2. Click "Enable Microphone." Your browser will ask permission. Audio is processed locally — nothing is uploaded.

3. Pluck one string. Play with your finger (not a pick) for cleanest detection — the fundamental is stronger and harmonics are less likely to confuse the tuner. The display shows the detected note (e.g., "E1"), the actual frequency in Hz, and how many cents you are sharp or flat. Green ±5¢ is in tune; yellow ±15¢ is close; red is more than 30¢ off.

4. Adjust the tuning peg. The display tells you UP or DOWN. Bass strings are stiff and slow to respond — small adjustments only. Pluck, check, adjust, repeat. The display freezes at the last detected reading after the note decays, so you can look up from the instrument and read what you played without rushing.

5. If the tuner jumps between notes, lock the target string manually. Bass strings produce strong harmonics that can fool auto-detection into jumping to the second or third harmonic (one or two octaves higher). Locking the string forces the tuner to compute cents-offset from your chosen target only.

Why low-bass tuning is technically harder

A note's pitch is determined by the time interval between successive peaks of its waveform — the period. The low E on a 4-string bass has a period of about 24 milliseconds; the low B on a 5-string is about 32 milliseconds. To detect these reliably, the analysis window has to contain at least 4-5 full periods of the wave. At the standard 44,100 samples-per-second audio rate that means about 1,500 samples per cycle for the low B, so an analysis window needs to be at least 6,000-8,000 samples long.

Most general-purpose tuners — the kind built into guitar apps — use a 4,096-sample window. That's adequate for guitar (where the lowest open string E2 has a period of ~12 ms and the window contains ~7-8 cycles), but borderline for bass and basically inadequate for the low B. This tuner doubles the window to 8,192 samples, which gives 5-6 cycles of a 30 Hz note — enough for the autocorrelation algorithm to find a confident peak.

The trade-off is a slightly slower response — 8,192 samples is about 186 ms of audio, so the tuner needs at least that long of a sustained note before reading. In practice this barely matters: bass notes last seconds, not milliseconds. The longer window is the right call for the instrument.

Bass tuning reference table

Bass notation is conventionally written one octave higher than the actual sounding pitch — bass guitar is a transposing instrument. So a note written on the bottom line of the bass clef (E2) is actually played at E1.

The 12th-fret test (intonation)

Once your open strings are in tune, play each string at the 12th fret and check the reading. The 12th-fret note should be exactly one octave above the open string — same note name, with the octave number raised by one. So open E1 should give E2 at the 12th fret; open A1 should give A2; and so on.

If the 12th-fret reading is not exactly the octave — if it's a few cents sharp or flat compared to the open string — your bass has an intonation problem. The fretted note is being raised by an amount that depends on the geometry of the bridge saddle. To fix it, adjust the bridge saddle for that string: move it back (away from the neck) if the 12th-fret note is sharp, forward if it's flat. Most bass bridges have small screws for this adjustment.

Intonation drifts when string gauges change, when the neck has been adjusted, or when the instrument has been knocked around. Re-checking the 12th-fret note after any of these is a good habit. A bass that intonates correctly across all four (or five, six) strings is one of the cheapest setup wins a working musician can make.

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