Convert semitones to a frequency ratio, cents, and a resulting pitch — for transposition, tuning, and synthesizer work.
The Pitch Semitone Ratio Calculator converts between semitones, cents, frequency ratios and tape-style playback speed. Shifting a recording up 2 semitones multiplies every frequency by 1.1225; a record played 5% fast rises 0.84 semitones. This calculator gives you those numbers directly.
Type a starting frequency to see the shifted pitch and its note name.
One semitone is a frequency ratio of 2^(1/12) ≈ 1.05946; one octave (12 semitones) is exactly ×2. So ratio = 2^(semitones/12), semitones = 12·log₂(ratio), and cents = semitones × 100. For tape-style speed changes pitch and tempo move together, so speed % = ratio × 100.
Know the ratio for +/− semitones.
Retune samples.
Speed errors in pitch terms.
Understand interval sizes.
| Conversions | Semitones ↔ cents ↔ ratio ↔ speed % |
|---|---|
| Extras | Starting-frequency result with note name |
About 84.5 cents (0.845 semitones).
2^(7/12) ≈ 1.4983 in equal temperament.
ratio = 2^(semitones/12) — the standard equal-tempered tuning formula, where 12 semitones (one octave) exactly doubles the frequency.
A cent is 1/100th of a semitone — a finer unit used for describing very small tuning differences.
This tool runs entirely in your browser using the Web Audio API. Nothing is uploaded, stored or shared — there is no server to send your file to, so it works offline once the page has loaded.
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