E4 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 E4 is exactly 440 × 2^(-5/12) Hz. Under alternative references the note shifts with the reference: at A4 = 432 Hz, E4 becomes 323.63 Hz.
E in every octave
| Note | Frequency | MIDI | Piano key |
|---|---|---|---|
| E1 | 41.20 Hz | 28 | 8 |
| E2 | 82.41 Hz | 40 | 20 |
| E3 | 164.81 Hz | 52 | 32 |
| E4 ← | 329.63 Hz | 64 | 44 |
| E5 | 659.26 Hz | 76 | 56 |
| E6 | 1318.5 Hz | 88 | 68 |
| E7 | 2637.0 Hz | 100 | 80 |
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 D♯4 at 311.13 Hz; one semitone up is F4 at 349.23 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.