Online Guitar Tuner — Free Mic-Based Chromatic Tuner
Tune your guitar in real time using your device microphone. Chromatic autocorrelation pitch detection, precise cents display, signal strength meter, A430–A450 calibration, 10 alternate tunings, auto string detection, and note history. Works on acoustic, electric, and bass guitar. No download, no signup.
Guitar Tuner
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What makes this guitar tuner different from tuner-online.com and guitarapp.com
How to tune your guitar with this tuner
LazyTools vs other free online guitar tuners
| Feature | LazyTools | tuner-online.com | guitarapp.com | guitar-tuner.org | musicca.com |
|---|---|---|---|---|---|
| Cents accuracy display | ✅ Numeric + needle | ✅ Needle only | ✅ Yes | ✅ Yes | ❌ Needle only |
| Signal strength meter | ✅ Yes | ❌ No | ❌ No | ❌ No | ❌ No |
| Alternate tunings | ✅ 10 tunings | Standard only | ✅ Many | ✅ Yes | Standard only |
| Calibration (A430–A450) | ✅ Yes | ❌ No | ❌ No | ❌ No | ❌ No |
| Note history log | ✅ Yes | ❌ No | ❌ No | ❌ No | ❌ No |
| Chromatic mode | ✅ Yes | ✅ Yes | ✅ Yes | ✅ Yes | ✅ Yes |
| Auto string detection | ✅ Yes | ✅ Yes | ✅ Yes | ✅ Yes | ✅ Yes |
| No signup required | ✅ Always | ✅ Yes | ✅ Yes | ✅ Yes | ✅ Yes |
| No audio upload/storage | ✅ Local only | ✅ Yes | ✅ Yes | ✅ Yes | ✅ Yes |
Guitar string frequencies by tuning — target Hz for each string
| Tuning | String 6 (low) | String 5 | String 4 | String 3 | String 2 | String 1 (high) |
|---|---|---|---|---|---|---|
| Standard (EADGBE) | E2 82.41 | A2 110.00 | D3 146.83 | G3 196.00 | B3 246.94 | E4 329.63 |
| Drop D (DADGBE) | D2 73.42 | A2 110.00 | D3 146.83 | G3 196.00 | B3 246.94 | E4 329.63 |
| Open G (DGDGBD) | D2 73.42 | G2 98.00 | D3 146.83 | G3 196.00 | B3 246.94 | D4 293.66 |
| Open D (DADF#AD) | D2 73.42 | A2 110.00 | D3 146.83 | F#3 185.00 | A3 220.00 | D4 293.66 |
| DADGAD | D2 73.42 | A2 110.00 | D3 146.83 | G3 196.00 | A3 220.00 | D4 293.66 |
| Half Step Down (Eb) | Eb2 77.78 | Ab2 103.83 | Db3 138.59 | Gb3 185.00 | Bb3 233.08 | Eb4 311.13 |
| Drop C (CADGBE) | C2 65.41 | A2 110.00 | D3 146.83 | G3 196.00 | B3 246.94 | E4 329.63 |
Guitar Tuner Guide — How Pitch Detection Works and Why Cents Matter
A microphone-based guitar tuner captures audio from your device's microphone, analyses the frequency of the sound, and compares it to the target frequency for the nearest note. The quality of pitch detection depends heavily on the algorithm used to extract the fundamental frequency from the waveform.
Autocorrelation pitch detection
This tuner uses an autocorrelation algorithm applied to the raw audio waveform captured by the Web Audio API's AnalyserNode. Autocorrelation measures how similar a signal is to a delayed version of itself. For a periodic signal (like a guitar string), strong correlation appears at the delay equal to the period of the fundamental frequency. The detected period is converted to a frequency: frequency = sampleRate / period. This approach reliably detects the fundamental pitch even in the presence of harmonics — which are the overtones that give the guitar its timbre.
What are cents and why do they matter?
A cent is 1/100 of a semitone. There are 100 cents between any two adjacent notes (e.g., between E and F, or between A and A#). A reading of +10 cents means the string is 10/100 of a semitone sharp — audible to a trained ear but not immediately obvious to a beginner. Professional hardware tuners aim for ±0.1 cent accuracy. Browser-based tuners using laptop microphones typically achieve ±2–5 cents, which is entirely sufficient for playing in tune. This tuner displays the exact cents deviation as a number alongside the needle so you can see exactly how close you are.
What is A432 tuning?
A432 means the reference pitch A4 is set to 432 Hz rather than the standard 440 Hz (concert pitch). This shifts every note slightly flat relative to A440. Some musicians, composers, and listeners prefer A432 for its slightly warmer, more relaxed sound quality. It is also associated with certain meditative music traditions. Some historical recordings and classical instruments predate the 1939 international standardisation of A440. The calibration slider on this tuner lets you set any reference pitch between 430 Hz and 450 Hz, covering A432, A440, A442 (common in German orchestras), and A444.
Online guitar tuner free no download — how it works in the browser
The entire pitch detection pipeline runs in your browser using the Web Audio API. When you click Start Tuner, navigator.mediaDevices.getUserMedia({audio: true}) requests microphone access. The audio stream is connected to an AudioContext and an AnalyserNode. Every 100ms, getFloatTimeDomainData() copies the waveform into a buffer. The autocorrelation algorithm processes this buffer to detect the fundamental frequency. No audio data ever leaves your device.
Guitar tuner — 8 questions answered
Uses your microphone via the Web Audio API. An autocorrelation algorithm detects the fundamental frequency from the waveform. The frequency is compared against target notes to identify the string and cents deviation.
A cent is 1/100 of a semitone. +10 cents means 10% of a semitone sharp. The needle turns green within ±5 cents. Professional tuning targets ±2 cents.
Standard, Drop D, Open G, Open D, DADGAD, Half Step Down (Eb), Full Step Down (D), Drop C, Open E, and C Standard. Each shows target notes and Hz for all 6 strings.
A432 sets the reference pitch to 432 Hz instead of standard 440 Hz, shifting all notes slightly flat. Some prefer its warmer sound. Drag the calibration slider to 432 to use it.
Pluck one string at a time gently near the middle. Wait 1-2 seconds for pitch to stabilise. Tune in a quiet environment. Always tune up to the note from below — strings hold their tuning better this way.
Signal strength shows how loud the microphone input is. Too quiet and pitch detection becomes unreliable. Too loud and the signal clips. Aim for the middle of the meter.
No. All processing happens locally via the Web Audio API. No audio data leaves your device. Microphone access is released when you stop the tuner.
LazyTools Guitar Tuner is 100% free. No download, no account, no signup. Chromatic pitch detection, cents display, 10 alternate tunings, A432-A444 calibration, signal strength meter, note history.