F♯4 at a glance
All values assume twelve-tone equal temperament at the international standard pitch of A4 = 440 Hz. In that system every semitone has the same size - a frequency ratio of 2^(1/12) - so F♯4 is exactly 440 × 2^(-3/12) Hz. Under alternative references the note shifts with the reference: at A4 = 432 Hz, F♯4 becomes 363.27 Hz.
F♯ in every octave
| Note | Frequency | MIDI | Piano key |
|---|---|---|---|
| F♯1 | 46.25 Hz | 30 | 10 |
| F♯2 | 92.50 Hz | 42 | 22 |
| F♯3 | 185.00 Hz | 54 | 34 |
| F♯4 ← | 369.99 Hz | 66 | 46 |
| F♯5 | 739.99 Hz | 78 | 58 |
| F♯6 | 1480.0 Hz | 90 | 70 |
| F♯7 | 2960.0 Hz | 102 | 82 |
Each octave doubles the frequency - the simplest relationship in music, and the reason notes an octave apart sound like “the same note, higher”.
Neighboring notes
One semitone down is F4 at 349.23 Hz; one semitone up is G4 at 392.00 Hz. Need a frequency between notes, or a different waveform? The tone generator plays anything from 20 Hz to 20 kHz; the note ↔ frequency converter does the math both directions, and the chromatic tuner listens to your instrument and shows the offset in cents.