D♯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 D♯4 is exactly 440 × 2^(-6/12) Hz. Under alternative references the note shifts with the reference: at A4 = 432 Hz, D♯4 becomes 305.47 Hz.
D♯ in every octave
| Note | Frequency | MIDI | Piano key |
|---|---|---|---|
| D♯1 | 38.89 Hz | 27 | 7 |
| D♯2 | 77.78 Hz | 39 | 19 |
| D♯3 | 155.56 Hz | 51 | 31 |
| D♯4 ← | 311.13 Hz | 63 | 43 |
| D♯5 | 622.25 Hz | 75 | 55 |
| D♯6 | 1244.5 Hz | 87 | 67 |
| D♯7 | 2489.0 Hz | 99 | 79 |
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 D4 at 293.66 Hz; one semitone up is E4 at 329.63 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.