Chromatic Tuner (Free, Online)
Play a note near your microphone and this free chromatic tuner instantly detects the pitch of any instrument — guitar, bass, ukulele, violin and more. Reference pitch (A=440Hz etc.) is adjustable, and all audio is processed entirely in your browser and never sent to a server.
What this chromatic tuner does
Play a single note into your microphone and this tool tells you which note it is and how far it sits from true pitch, measured in cents. It works for guitar, bass, ukulele and violin as well as for the voice, and the reference pitch can be changed. The audio is analysed entirely inside your browser and never reaches a server.
**The first thing worth knowing is that A = 440 Hz is a convention, not a law of physics.** Four hundred and forty is the international standard, but many orchestras tune to 442 or 443 Hz, and early-music ensembles often work around 415 Hz. When playing together, **everyone sharing the same reference matters far more than that reference being 440**. Practising alone, 440 is fine; before joining others, check what they are using.
**The second is that a tuner reading "perfect" is not the same as a chord sounding clean.** Tuners work in equal temperament, where the major third sits roughly fourteen cents above the naturally consonant interval of just intonation. That is why open strings tuned faultlessly by a tuner can still leave certain chords sounding slightly muddy — it is the tuning system, not your playing. In practice, players move a few cents either way depending on a note's role in the chord.
**Microphone tuners are also pulled about by ambient sound and overtones.** In a room where others are playing, the reading wanders; on low strings, the tuner may lock onto an overtone rather than the fundamental and display the note an octave high. A quiet room and one clearly sounded note give the most dependable result.
How to use it
- Check the reference pitch **If you are playing with others, agree the reference first.** Alone, leaving it at 440 Hz is fine.
- Allow microphone access The browser will ask. Nothing leaves your device.
- Sound one note at a time **Several strings at once cannot be read.** Damp the others and sound each in turn.
- Adjust while watching the cents **Bring the string up to pitch from slightly below until the reading settles in the centre.**
Tips for getting more out of it
- For the most accurate reading, play in a quiet room and pluck a single string or sing a single sustained note. Playing a chord or multiple notes at once can confuse the fundamental-pitch detection.
- The reference pitch defaults to 440Hz, but orchestras and wind bands sometimes tune to around 442Hz — adjust it to match the ensemble you're playing with.
- The closer the needle sits to the center and the cents reading to 0, the more accurate the pitch. Anything within ±5 cents shows as "In Tune".
- If detection feels unstable due to microphone sensitivity or background noise, try moving the instrument closer to the microphone or finding a quieter spot.
- Guitars and ukuleles can be fine-tuned not just on open strings but also while fretting a note, which is useful for checking intonation up the neck.
When this is useful
Tuning a string instrument before playing
**Guitars, basses, ukuleles and violins all drift, and the drift always shows up before you start.**
Learning the tendencies of a wind instrument
The same fingering moves with breath pressure; the tuner shows which way a note tends to fall.
Checking vocal pitch
**A note you believe to be in tune becomes visibly sharp or flat.**
Matching an ensemble reference
Practise at 415 Hz, 442 Hz or whatever the group uses.
Terms used here
- Reference pitch
- The frequency assigned to A4. **440 Hz is the international standard, but 442 Hz and 415 Hz are both in regular use.**
- Cent
- One hundredth of a semitone. **Within about five cents, an ordinary ear will not hear the difference.**
- Chromatic
- Able to identify every semitone rather than only a fixed set of strings.
- Equal temperament
- An octave divided into twelve equal steps. **This is the system a tuner measures against.**
- Just intonation
- Tuning in which intervals are simple whole-number frequency ratios. **The equal-tempered major third sits about fourteen cents above it.**
- Overtone
- A frequency component at a whole-number multiple of the fundamental. **On low strings a tuner may lock onto one and read an octave high.**
Frequently Asked Questions
Side Note — How A=440Hz Became the Standard
The now-ubiquitous "A=440Hz" reference pitch was proposed at an international conference in London in 1939 and formally adopted by the International Organization for Standardization (ISO) as ISO 16 in 1955. Before that, the reference pitch varied widely between orchestras and regions, so it wasn't unusual for the same piece to sound at a noticeably different pitch depending on where it was performed.
The pitch-detection technique behind this tool is a classic signal-processing algorithm called autocorrelation. It shifts a waveform against a copy of itself by small time increments and measures how closely they match at each shift; the shift with the strongest match reveals the period of the fundamental frequency — the pitch we perceive. Because instrument tones are rich in overtones, naive frequency analysis often mistakes an overtone for the fundamental, and autocorrelation is well known for being more robust against that error.
Many people feel uneasy about tools that use a microphone, but this tuner never stores a recording and never sends audio to an external server. Every bit of analysis happens locally inside your browser, and the captured audio is discarded the instant you close the page.
A metronome is the natural companion for keeping steady time, while a note-to-frequency reference table is handy when you want to look up the exact frequency of a specific note before you start tuning. Combining pitch, rhythm, and frequency knowledge makes day-to-day instrument practice noticeably more efficient.