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What tuner accuracy means
Pitch error is commonly measured in cents. One semitone contains 100 cents. A reading of −5 cents is slightly flat, while +5 cents is slightly sharp. The smaller the error a tuner can detect reliably, the more precise its measurement.
How accurate do you need to be?
| Use | Practical target | Priority |
|---|---|---|
| Casual practice | Centered and stable within a few cents | Fast, repeatable tuning |
| Rehearsal or performance | Consistent readings in the playing environment | Noise rejection and visibility |
| Recording | Small, repeatable error across every take | Check before each take |
| Intonation setup | Fine, repeatable measurement | Strobe-style or high-resolution tuner |
| Ear training | Electronic verification after listening | Learn pitch relationships |
There is little practical value in chasing a flickering zero while the string itself is changing pitch. A stable reading and consistent technique matter more than a large accuracy number on a product page.
Why a plucked string does not have one fixed pitch
A string often begins slightly sharp immediately after a strong attack, then settles and slowly decays. Low or loose strings show this effect more clearly. Tune during the stable part of the note rather than the first instant or final weak vibration.
Factors that affect the reading
- Pick attack: hitting too hard temporarily raises pitch.
- Background noise: a microphone tuner may detect voices, music, or another string.
- Sympathetic vibration: unused strings can ring along with the target.
- Signal strength: a very quiet or decaying note produces unstable detection.
- Battery and hardware: weak batteries or poor contact can affect dedicated tuners.
- Calibration: a tuner set to a nonstandard reference will disagree with A=440 equipment.
How to get a more accurate result
- Tune in a quiet place or use a vibration/direct-input tuner in a noisy environment.
- Mute the five strings you are not measuring.
- Pluck with moderate, consistent force.
- Let the initial attack settle briefly.
- Approach the target from below with small key movements.
- Repeat all six strings after the first pass.
Online, clip-on, pedal, and strobe tuners
An online microphone tuner is convenient for everyday practice and can display target strings clearly. A clip-on senses vibration and performs better around room noise. A pedal tuner receives an electric instrument’s direct signal and can mute the output onstage. Strobe-style tuners offer fine visual sensitivity for setup work.
The best choice depends on the environment, not just a published accuracy specification. Read Clip-On vs Online Guitar Tuner for a practical comparison.
Accuracy versus guitar intonation
A perfectly tuned open string does not guarantee every fretted note will be perfect. Fret placement, string stiffness, action height, finger pressure, and saddle position affect fretted pitch. If chords become increasingly wrong higher on the neck, use the guitar intonation guide.
Equal temperament and chord compromises
Modern guitars normally use equal temperament, which divides the octave into twelve equal semitones. This lets players use every key, but some intervals are deliberately slight compromises compared with pure natural ratios. A tuner can show every open string centered while certain chord voicings still produce audible beating.
What “in tune” should mean in practice
For normal playing, aim for readings that settle near the center, remain repeatable when you repluck, and produce familiar chords without one string standing out. For repair measurements, use a more sensitive tuner and identical picking pressure for every comparison.
What this site's tuner actually measures
The current detector looks for periodic audio between 45 and 390 Hz and compares it with the six open-string targets in your selected preset. That range covers the supplied six-string presets, including low A1 and high E4. It does not cover every possible fretted note or make this a full-range chromatic tuner. The meter turns green within ±5 cents; the display threshold is not a guarantee of microphone accuracy.
Reproducible software checks
On November 11, 2026, we checked the pitch-detection function with 108 generated sample buffers. Each buffer contained 4,096 samples at 44.1 or 48 kHz. We used nine pitches from 55 to 329.6276 Hz, three starting phases, and either a sine wave or a fundamental with second and third harmonics at 35% and 15% of its amplitude. A separate silent buffer was rejected.
| Sample rate | Signal | Cases | Largest absolute error |
|---|---|---|---|
| 44100 Hz | Sine wave | 27 | <0.01 cents |
| 44100 Hz | Fundamental plus harmonics | 27 | <0.01 cents |
| 48000 Hz | Sine wave | 27 | <0.01 cents |
| 48000 Hz | Fundamental plus harmonics | 27 | <0.01 cents |
This is a software check, not a hardware accuracy specification. It bypasses the microphone, room acoustics, device clock, browser audio processing, and the display's smoothing. Real strings have attacks, decay and noise that these ideal signals do not reproduce. The result does not mean a phone can tune a guitar to 0.01 cents.
The check script and its exact input frequencies are public. Run it with Node.js to reproduce the calculations.
Compare readings fairly on your own guitar
- Set both tuners to the same reference pitch and tuning.
- Mute unused strings and pluck with the same moderate force.
- Compare the settled portion of several notes, rather than one moment of the attack.
- If the devices disagree consistently, check calibration and the input device before adjusting the guitar's setup.
For example, an A string at 111 Hz is about +15.67 cents relative to a 110 Hz A2 target: 1200 × log2(111 / 110). A one-hertz difference has a different cent value on another string, so comparing raw hertz differences alone can mislead.