How to Use Semitone Calculator
The Semitone Calculator supports two modes. Select the one that fits your task before entering values.
Mode 1 — Find semitone difference between two pitches:
- Choose Frequencies → Semitone Count from the mode selector.
- Enter two frequencies in Hz (e.g. 440 and 880), or enable note-name input and type note names such as A4 and A5.
- Select your tuning standard — 440 Hz, 432 Hz, or custom A4.
- Read the result — the Semitone Calculator displays the exact and rounded semitone count, the corresponding interval name, the pitch direction (up/down), and the frequency ratio.
Mode 2 — Calculate target frequency from a semitone shift:
- Choose Start Frequency + Semitones → Target Frequency from the mode selector.
- Enter a starting frequency in Hz or a starting note name.
- Enter the semitone shift — positive numbers raise pitch, negative numbers lower it.
- Read the result — the Semitone Calculator shows the target frequency, the closest note name, the interval, and the frequency ratio.
Formula & Theory - Semitone Calculator
The Semitone Calculator is based on equal temperament acoustics. All twelve semitones within an octave divide the 2:1 frequency ratio equally on a logarithmic scale.
Semitone Count from Two Frequencies
n = 12 × log₂(f₂ / f₁)Target Frequency from Semitone Shift
f_target = f_start × 2^(n / 12)Frequency Ratio for n Semitones
ratio = 2^(n / 12)| Symbol | Meaning |
|---|---|
| n | Number of semitones |
| f₁ | Starting (lower or reference) frequency in Hz |
| f₂ | Target or ending frequency in Hz |
| f_start | Starting frequency in Hz |
| f_target | Resulting frequency after shifting by n semitones |
Note Name to Frequency
Using the MIDI standard (C4 = MIDI 60, A4 = MIDI 69):
MIDI number = (octave + 1) × 12 + note_index
frequency = A4_ref × 2^((MIDI − 69) / 12)Interval Names
| Semitones | Interval |
|---|---|
| 0 | Unison (P1) |
| 1 | Minor 2nd (m2) |
| 2 | Major 2nd (M2) |
| 3 | Minor 3rd (m3) |
| 4 | Major 3rd (M3) |
| 5 | Perfect 4th (P4) |
| 6 | Tritone (A4 / d5) |
| 7 | Perfect 5th (P5) |
| 8 | Minor 6th (m6) |
| 9 | Major 6th (M6) |
| 10 | Minor 7th (m7) |
| 11 | Major 7th (M7) |
| 12 | Octave (P8) |
Assumptions and Limits
The Semitone Calculator uses 12-tone equal temperament. Results may differ slightly from just intonation or meantone temperament, where intervals are tuned to simpler frequency ratios. Enharmonic equivalents such as C# and Db are treated as identical.
Use Cases for Semitone Calculator
The Semitone Calculator is a practical tool across music production, performance, education, and sound design:
- Instrument tuning — Verify whether two notes played together form the intended interval, or check how far a stringed instrument is from the target pitch.
- Music production and transposition — Calculate the semitone shift needed to transpose a sample or plugin to a different key, then apply the value directly in your DAW.
- Sound design — Tune synthesizer oscillators and effects with precision, converting between Hz values and musical intervals.
- Music theory education — Visualize the frequency ratios behind intervals like the perfect fifth (7 semitones, ratio ≈ 1.498) and the octave (12 semitones, ratio = 2).
- Vocal coaching — Determine the interval a singer needs to reach from one note to another, expressed in semitones or as a named interval.
- Alternative tuning exploration — Switch to A4 = 432 Hz or a custom reference to explore how different tuning standards affect all note frequencies.
From quick interval checks to detailed frequency analysis, the Semitone Calculator provides clear, mathematically precise results for any pitch-related task.