Instrument Tuner — Mic Detection
Free online instrument tuner with microphone pitch detection, cents needle and presets for guitar, violin and more. Private analysis. Runs in browser.
How it works
Real-time time-domain autocorrelation (Normalized Square Difference Function) pitch detection with sub-sample parabolic peak interpolation. Audio is processed purely inside your local browser memory via Web Audio API with zero recording or server transmission.
Tune your acoustic and electric instruments with real-time microphone pitch tracking. Powered by time-domain autocorrelation DSP with sub-cent parabolic peak interpolation, this tuner detects the fundamental pitch of strings across a wide musical spectrum—from the deep growl of a 5-string bass ($B_0 \approx 30.9\text{ Hz}$) to the highest registers of a violin ($E_5 \approx 659.3\text{ Hz}$ and beyond).
How to Tune Your Instrument
- Select Your Instrument Preset: Choose your instrument from the dropdown menu (e.g., Guitar, Bass, Ukulele, Violin, or Chromatic).
- Enable Microphone: Click Start Tuner (Microphone) and grant browser microphone permission. Audio is processed purely in your browser’s local memory with zero server uploads.
- Pluck One String at a Time:
- Damp or mute all other strings with your palm to eliminate sympathetic resonance.
- Pluck gently near the 12th fret for a clean, warm fundamental tone with minimal harsh pick attack.
- Read the Gauge:
- Needle centered & Green indicator: In tune within your chosen tolerance ($\pm 3$ cents by default).
- Needle to the left (Amber / Flat): Pitch is too low; tighten the tuning peg clockwise or counterclockwise according to your headstock orientation.
- Needle to the right (Red / Sharp): Pitch is too high; loosen the peg slightly below pitch, then tune up into pitch to maintain string tension on the post.
Instrument String Frequencies ($A_4 = 440\text{ Hz}$)
| Instrument | String | Note | Ideal Frequency |
|---|---|---|---|
| Guitar (Standard) | 6th String | $E_2$ | 82.41 Hz |
| 5th String | $A_2$ | 110.00 Hz | |
| 4th String | $D_3$ | 146.83 Hz | |
| 3rd String | $G_3$ | 196.00 Hz | |
| 2nd String | $B_3$ | 246.94 Hz | |
| 1st String | $E_4$ | 329.63 Hz | |
| Guitar (Drop D) | 6th String | $D_2$ | 73.42 Hz |
| Bass Guitar (4-String) | 4th String | $E_1$ | 41.20 Hz |
| 3rd String | $A_1$ | 55.00 Hz | |
| 2nd String | $D_2$ | 73.42 Hz | |
| 1st String | $G_2$ | 98.00 Hz | |
| Bass Guitar (5-String) | 5th String | $B_0$ | 30.87 Hz |
| Ukulele (Standard C) | 4th String | $G_4$ | 392.00 Hz |
| 3rd String | $C_4$ | 261.63 Hz | |
| 2nd String | $E_4$ | 329.63 Hz | |
| 1st String | $A_4$ | 440.00 Hz | |
| Violin | 4th String | $G_3$ | 196.00 Hz |
| 3rd String | $D_4$ | 293.66 Hz | |
| 2nd String | $A_4$ | 440.00 Hz | |
| 1st String | $E_5$ | 659.25 Hz | |
| Cello | 4th String | $C_2$ | 65.41 Hz |
| 3rd String | $G_2$ | 98.00 Hz | |
| 2nd String | $D_3$ | 146.83 Hz | |
| 1st String | $A_3$ | 220.00 Hz |
The Mathematics of Cents Deviation
In 12-Tone Equal Temperament, every semitone is logarithmically equal to 100 cents:
$$\text{cents} = 1200 \times \log_2\left(\frac{f_{\text{detected}}}{f_{\text{target}}}\right)$$
- If detected frequency matches target exactly, $\log_2(1) = 0$, so $\text{cents} = 0$.
- If $f_{\text{detected}} = 442.5\text{ Hz}$ and target $A_4 = 440.0\text{ Hz}$, the deviation is $+9.8$ cents (sharp).
- If $f_{\text{detected}} = 437.5\text{ Hz}$, the deviation is $-9.9$ cents (flat).
Our tuner combines IEC-standardized exponential ballistics with instantaneous correlation tracking to dampen mechanical jitter while remaining immediately responsive to continuous peg adjustments.
Frequently asked questions
How does microphone autocorrelation pitch detection work?
Autocorrelation measures how closely an audio waveform correlates with a time-shifted copy of itself. When the time shift equals the fundamental period of a vibrating musical string or vocal fold, the correlation reaches a sharp peak. By calculating the fundamental period directly in the time domain, the tuner determines the exact fundamental frequency and interpolates sub-sample parabolic peaks to achieve sub-cent tuning resolution.
Why is autocorrelation superior to FFT peak-picking for acoustic instruments?
Acoustic instruments like guitars, cellos, and upright basses produce rich harmonic overtone series where the fundamental frequency is often much weaker in amplitude than the second or third harmonics. An FFT (Fast Fourier Transform) peak-picker often locks onto the loudest harmonic (the octave or fifth), causing erratic octave-jumping. Time-domain autocorrelation (specifically the Normalized Square Difference Function) tracks the underlying periodic repetition of the entire composite waveform, locking solidly onto the true musical fundamental even when the fundamental is acoustically suppressed.
Does this instrument tuner record or upload my audio?
No. All audio acquisition and digital signal processing run strictly inside your browser local memory via the Web Audio API. No microphone data, recordings, audio snippets, or analytical telemetry are ever uploaded or transmitted to any server. When you close the tab or stop the tuner, the microphone stream is immediately released.
How can I tune low bass strings (E1 or B0) reliably with a laptop or phone mic?
Small built-in laptop and phone microphones often roll off frequencies below 80 Hz, making the fundamental of a low E1 (41.2 Hz) or B0 (30.9 Hz) acoustically quiet. Our tuner incorporates a 4096-sample buffer and harmonic pattern correlation to reconstruct the fundamental pitch from overtone intervals. For optimal results, pluck the string firmly over the 12th fret with your thumb, allow the attack transient to settle for a half-second, and mute all idle strings with your palm.
What are cents in musical tuning?
In 12-Tone Equal Temperament (12-TET), an octave is divided into 12 semitones, and each semitone is divided into 100 cents. A single cent represents a frequency ratio of approximately 1.000578. Human ears generally cannot distinguish pitch variations smaller than 3 to 5 cents in melody, which is why a reading within ±3 cents is considered in tune for performance.