Concert Pitch Generator — A440, A432 & A442 Reference Tones
Generate precision concert pitch reference tones in A440, A432, A442 and historical Baroque pitches. Reference drones for acoustic instruments.
Tool controls
Protect your hearing. Start at a low volume. Never raise the volume to make a tone audible. Levels are shown in dBFS, relative to full scale — not SPL.
How it works
Pitch references are computed in client-side Web Audio using 12-Tone Equal Temperament relative to your selected reference standard (A4 = 400 Hz – 480 Hz). Tones offer warm harmonic filtering or pure sinusoids with smooth micro-fade envelopes to eliminate digital onset clicks.
On this page
This concert pitch generator plays reference tones for tuning by ear at A440, A432, A415, A430, A442 or any reference between 400 and 480 Hz, with per-string notes for eight common instruments and a bank of Solfeggio tones. Everything is synthesized locally with the Web Audio API, so nothing is uploaded.
How to use it
- Set the reference pitch. Tap a chip for 440 Hz (ISO Standard), 432 Hz (Verdi Pitch), 415 Hz (Baroque), 430 Hz (Classical) or 442 Hz (European), or type a custom value from 400 to 480 Hz in 0.1 Hz steps. Every note recalculates from that number.
- Pick an instrument. The selector covers guitar (standard and Drop D), four- and five-string bass, violin, viola, cello and ukulele. Each string card shows the note name and the exact frequency at the current reference.
- Play a single string reference. Click a card to hear that note, or press Strum All Strings to step through the instrument’s strings one note every 1.2 seconds.
- Choose how the tone behaves. Continuous Drone holds a steady pitch so you can sustain a note against it; Plucked String plays a 2.5-second decaying note for a quick check.
- Choose the timbre and level. In drone mode, Warm Acoustic String is a filtered triangle wave and Pure Sine Wave strips out the harmonics. The volume slider starts at 50%.
- Play or stop. The dashboard shows the active note and frequency, and the Stop button silences the engine. The Solfeggio tab holds ten fixed meditation tones on the same engine.
Concert pitch references and how far they sit from A440
Every reference on the page is a 12-tone equal temperament grid anchored to one number: the frequency of A4. Published orchestral pitches differ by a small fraction of a semitone, and the cents column below is the plain arithmetic 1200 × log2(f / 440).
| Reference | Typical use | Offset from A440 |
|---|---|---|
| 440 Hz A4 | ISO 16 standard pitch, most modern ensembles | 0 cents |
| 442 Hz A4 | Many European orchestras and some US ensembles | +7.9 cents |
| 432 Hz A4 | Verdi-style and “scientific” pitch, common in meditation practice | −31.8 cents |
| 430 Hz A4 | Classical-era pitch | −39.8 cents |
| 415 Hz A4 | Baroque pitch, close to a semitone below modern | −101.3 cents |
ISO 16:1975 fixed standard musical pitch at A4 = 440 Hz with a tolerance of 0.5 Hz, and the chip labeled 440 Hz reproduces exactly that. The spread between 440 and 442 is smaller than the tolerance of many instrument tuning systems: 7.9 cents is less than a tenth of a semitone, so an ensemble can move between them without changing fingerings. A415 is the outlier at just over a semitone below A440, which is why period-instrument players often treat it as a transposing reference rather than a small adjustment.
Tuning by ear with a drone
Two tones that are close in frequency produce a beat at the difference between them, and that pulse is the most accurate tuning indicator you can hear. The drone mode exists for this comparison: the reference stays fixed while your instrument moves.
- At 442 Hz against a 440 Hz drone, the beat rate is 442 − 440 = 2 per second.
- At 441 Hz it is 1 per second, and at 440.3 Hz it is one pulse every 3.3 seconds.
- At perfect unison the pulse stops, and any audible beating means the two pitches are still apart.
The method changes with the instrument. On guitar or bass, start the drone, then pluck the open string and let it ring; because the plucked note decays, you listen for the beat pattern in the first two or three seconds and re-pluck as you adjust the peg. On violin, viola, cello or double bass, draw a long, even bow stroke with a light contact point so the open string sustains against the drone and the beats stay steady. Wind and brass players usually play the reference first, then match the pitch from memory and stop the tone to check whether the note drifts. Set the timbre to Pure Sine Wave for this work: a sine has no upper partials, so the only beating you hear is between the two fundamentals. The same drone is a useful practice partner for scales and long tones, because every interval beats slightly when it is out of tune, not just the unison.
For string players who want a visual cent readout, the violin family has dedicated tuner pages with microphone input. This page stays a listening reference so it does not duplicate them.
The Solfeggio tab
The second tab holds ten fixed tones: 174, 285, 396, 417, 432, 528, 639, 741, 852 and 963 Hz, each with a short label. They are traditionally used for relaxation and meditation, and 432 Hz also appears in the tuning strip as an ordinary A4. They are not tuning standards, and they should not be used for instrument intonation work; use the reference strip and its 12-TET note grid instead.
Accuracy, limits and troubleshooting
- Frequency accuracy. Each note is computed as reference × 2^((midi − 69)/12) and played by an oscillator at the audio sample rate. The digital ratio is exact, so any small error comes from the device clock, which is far below one cent at musical frequencies.
- Timbre changes the beat pattern. Warm Acoustic String adds odd harmonics, which can make two slightly detuned tones sound thicker before the fundamental beats become obvious. Pure Sine Wave gives the cleanest comparison.
- Low strings need real bass reproduction. Bass E1 at 41.2 Hz, cello C2 at 65.4 Hz and even guitar E2 at 82.4 Hz are outside the useful range of phone and laptop speakers. The tone still plays, but you may hear only harmonics or nothing at all. Use headphones or full-range speakers.
- One tone at a time. The engine is a reference player, not a polyphonic instrument, and Strum All Strings steps through the strings in sequence rather than sounding them together.
- Mobile browsers start silent. The first Play press also starts the audio context, so nothing sounds until you tap it. Stop cancels the tone cleanly with a short fade, which avoids the click of an abrupt cut.
- Reference, not measurement. There is no microphone analysis and no cent readout here. If you want a needle or a cents display, use one of the tuner pages with a live input.
- Fixed-pitch instruments. Pianos, organs and marimbas cannot be retuned per note from a browser, so use the reference to check which way a tuning has drifted before calling a technician.
Related tools
- Tone Generator: any frequency with sweep, dual-tone and pan controls when you need a precise reference off the pitch grid.
- Waveform Generator: build the harmonic content of a reference tone and see the resulting wave shape.
- Audio Spectrum Analyzer: watch the reference and your instrument peaks side by side to see how far apart they are.
- Violin Tuner: microphone-based tuning for violin, viola, cello and double bass with a visual cent readout.
Frequently asked questions
What is the difference between A440 and A432?
A440 (440 Hz) is the internationally adopted concert pitch standard ratified by the International Organization for Standardization (ISO 16 in 1955). A432 (432 Hz), advocated by Italian composer Giuseppe Verdi, tunes all notes approximately 31.8 cents lower. Proponents argue 432 Hz feels warmer and aligns with natural acoustic proportions, though both are mathematically consistent 12-TET tuning temperaments.
What was historical concert pitch before 440 Hz?
Before international standardization, pitch varied wildly by region and cathedral. Baroque instruments in the 17th and 18th centuries were typically tuned around A415 (roughly a semitone lower than modern pitch). Classical-era instruments during Mozart's time centered around A430. Modern symphony orchestras in Germany and Austria often tune up to A442 or A443 for brighter string projection.
How do I tune my guitar using reference tones?
Play the reference string note (e.g. 82.41 Hz for Low E) as a continuous drone. Pluck your guitar string and listen for acoustic 'beating' (a rhythmic throbbing in volume). As you turn your tuning peg closer to the exact pitch, the beats slow down. When the beating disappears completely, the string is in perfect unison.
What are Solfeggio frequencies?
Solfeggio frequencies are a sequence of sacred sound therapy tones based on historical Gregorian chants (such as 'Ut queant laxis'). While modern empirical acoustic science treats them as relaxation frequencies rather than medical cures, tones like 528 Hz and 432 Hz are widely utilized for meditation, breathwork, and deep focus.
Can I tune my violin online with reference tones?
Yes. Play the string reference for G, D, A or E in A440 or your chosen standard, bow the matching open string, and listen for beating between the two pitches. Slow the beats to a standstill by adjusting the peg, then confirm with double stops. This is a listening reference, so noisy rooms suit the microphone tuner better.