Online Tuner & Tuning Fork

How Does the Online Tuner Work?

The Online Tuner uses the Web Audio API to generate mathematically precise sine wave tones at exact musical frequencies. When you select a note and click "Play Note," the tool creates an AudioContext and an OscillatorNode configured to produce a sine wave at the target frequency. The tone is shaped with a gentle attack and release envelope using a GainNode that ramps the volume up over 50 milliseconds at the start and fades it down smoothly at the end. This envelope prevents the audible clicking that would occur from abruptly starting or stopping a waveform, producing a clean, musical tone similar to a real tuning fork.

The frequencies used in this tuner follow the standard A440 equal temperament tuning system, which is the international standard adopted by virtually all modern Western music. In this system, the note A4 is defined as exactly 440 Hz, and all other notes are derived using the formula f = 440 * 2^((n-69)/12), where n is the MIDI note number. This mathematical relationship ensures that each semitone is separated by a constant frequency ratio of the twelfth root of 2 (approximately 1.05946), creating twelve equally spaced steps within each octave.

Standard Guitar Tuning (EADGBE)

The standard tuning for a six-string guitar, from the lowest (thickest) string to the highest (thinnest), is E2-A2-D3-G3-B3-E4. The low E string (E2) vibrates at 82.41 Hz, the A string at 110 Hz, D at 146.83 Hz, G at 196 Hz, B at 246.94 Hz, and the high E string (E4) at 329.63 Hz. This tuning has been the standard for classical and acoustic guitar for centuries and provides an excellent balance of range, chord voicings, and playability. To tune your guitar, play each reference note from this tool and adjust the corresponding string until the pitches match perfectly with no wavering or beating.

Standard Ukulele Tuning (GCEA)

The standard ukulele tuning is G4-C4-E4-A4, with the G string tuned to a higher octave (re-entrant tuning). G4 is 392 Hz, C4 is 261.63 Hz, E4 is 329.63 Hz, and A4 is 440 Hz. This tuning gives the ukulele its characteristic bright, cheerful sound. Some ukulele players use "low G" tuning where the G string is tuned an octave lower (G3 at 196 Hz) for a deeper, fuller range. Both G notes are available in this tuner's note selection.

The A440 Concert Pitch Standard

The A440 tuning standard, where the note A above middle C is set to 440 Hz, was internationally standardized in 1955 by the International Organization for Standardization (ISO 16). Before this standardization, concert pitch varied significantly across time periods and regions. In the Baroque era, A was commonly tuned anywhere from 380 Hz to 420 Hz. Some modern orchestras, particularly in continental Europe, tune to A442 or A443 for a brighter sound. The 440 Hz standard provides a universal reference that allows musicians and instruments worldwide to play together in tune.

How to Tune by Ear

Tuning by ear is a fundamental musical skill that improves your pitch recognition over time. Play the reference tone and your instrument string simultaneously. If the two pitches are close but not identical, you will hear a pulsating effect called "beating" — the two sound waves alternately reinforce and cancel each other. The speed of the beating indicates how far off your string is: faster beating means a larger pitch difference. Slowly adjust your tuning peg while listening. As the string approaches the correct pitch, the beating slows down. When the two pitches match perfectly, the beating stops entirely, and you hear a single, steady tone. This method works best in a quiet environment where you can clearly hear both sounds.

Bass and Violin Tuning Notes

The note list runs from E1 to E5, which covers four common instruments rather than guitar alone. Standard four-string bass is E1 (41.20 Hz), A1 (55.00 Hz), D2 (73.42 Hz) and G2 (98.00 Hz) — an octave below the bottom four guitar strings. Violin is tuned in fifths: G3 (196.00 Hz), D4 (293.66 Hz), A4 (440.00 Hz) and E5 (659.26 Hz), and violinists conventionally tune the A string first from the 440 Hz reference, then tune the remaining strings to it by listening for a beat-free perfect fifth. Viola uses C3 (130.81 Hz), G3, D4 and A4, and cello uses the same four note names an octave lower. Very low reference tones are hard to judge on a phone speaker, which reproduces little below about 200 Hz — for bass strings use headphones, or tune to the note one octave up and check the octave by ear. Every frequency here is derived from the same equal-temperament formula, f = 440 × 2^((n−69)/12), where n is the MIDI Association note number and A4 = 440 Hz is the concert-pitch anchor standardised as ISO 16. Last updated: September 2026.

Why 440 Hz?

The choice of 440 Hz as the standard reference pitch was ultimately a practical compromise. When the ISO adopted it in 1955, many orchestras and instrument manufacturers had already settled on or near this frequency. The frequency 440 Hz sits comfortably in the middle of the human hearing range, is easy to reproduce electronically, and provides a balanced tonal character across the full range of orchestral instruments. While some musicians and alternative tuning advocates propose A432 Hz as more "natural" or "harmonious," there is no scientific evidence supporting these claims. The consistency of having a universal standard far outweighs any subjective tonal preference.