Note Name to Frequency Converter (Concert Pitch Supported)
Convert between note names (C4, A4, etc.) and frequencies (Hz) for free. Switch the reference pitch (A4 = 440Hz, 442Hz, and more) and check tuning deviation in cents.
Standard Pitch (A4 = 440Hz) Frequency Table by Note (Octaves 2-6)
Theoretical values calculated using 12-tone equal temperament. The highlighted A4 (440.00Hz) is the reference note.
| Note | 2 | 3 | 4 | 5 | 6 |
|---|---|---|---|---|---|
| C | 65.41 | 130.81 | 261.63 | 523.25 | 1,046.50 |
| C# | 69.30 | 138.59 | 277.18 | 554.37 | 1,108.73 |
| D | 73.42 | 146.83 | 293.66 | 587.33 | 1,174.66 |
| D# | 77.78 | 155.56 | 311.13 | 622.25 | 1,244.51 |
| E | 82.41 | 164.81 | 329.63 | 659.26 | 1,318.51 |
| F | 87.31 | 174.61 | 349.23 | 698.46 | 1,396.91 |
| F# | 92.50 | 185.00 | 369.99 | 739.99 | 1,479.98 |
| G | 98.00 | 196.00 | 392.00 | 783.99 | 1,567.98 |
| G# | 103.83 | 207.65 | 415.30 | 830.61 | 1,661.22 |
| A | 110.00 | 220.00 | 440.00 | 880.00 | 1,760.00 |
| A# | 116.54 | 233.08 | 466.16 | 932.33 | 1,864.66 |
| B | 123.47 | 246.94 | 493.88 | 987.77 | 1,975.53 |
Tips
- Middle C on a piano is "C4" in scientific pitch notation, which corresponds to MIDI note number 60. Use this as a reference when comparing against instrument tuning charts or the note numbers shown in DAW software.
- You can type a sharp as either "#" or "♯", and a flat as either "b" or "♭". Upper and lower case letters are treated the same.
- When using "Frequency → Note Name" as a makeshift tuner, the deviation is shown in green when within 5 cents, yellow when within 20 cents, and red beyond that, so you can see how far off you are at a glance.
- Since orchestras and opera houses use different reference pitches, switch the reference pitch dropdown to match the ensemble you're playing with (440Hz, 442Hz, 443Hz, etc.) before calculating.
Frequently Asked Questions
Side Note — The Hidden History Behind the Number 440Hz
The reference "A4 = 440Hz" might seem like an obvious given, but the number itself has no particular scientific necessity. It is essentially the product of a political compromise: representatives from various countries agreed on it at an international conference held in London in 1939, and it was only in 1955 that the International Organization for Standardization (ISO) formally adopted it as "ISO 16." Before that, France used 435Hz while other regions used even higher pitches, and this lack of a common standard hindered international performing activity.
Interestingly, reference pitch still isn't fully unified today. Many prestigious European orchestras, including the Vienna Philharmonic and the Berlin Philharmonic, use 442Hz or 443Hz, an expression of a phenomenon known as "pitch inflation." Tightening the strings further adds tension and brilliance to the sound, and this desire to make a stronger impression on audiences is thought to have gradually pushed reference pitch upward over time.
Things get even more complex with historically informed performance on period instruments from the Baroque era. Records reconstructed from organs and tuning forks of the time show that A4 varied by region and era, ranging from roughly 392Hz to 415Hz, considerably lower than the modern standard. This is why early music ensembles today often use 415Hz (roughly a semitone below modern A4) — it reflects a deliberate effort at historical authenticity.