Pitch Shift Playback Speed Calculator
If a recording changes pitch by semitones and cents through speed alone, what happens to its duration?
Method, formula and assumptions
Equal-tempered speed ratio = 2^((semitones + cents/100)/12). Frequency multiplies by the ratio, while playback duration divides by it. Positive shifts raise pitch and shorten duration.
Input definitions and supported units
- Upward shift (semitones): Measured or assumed numerical value, from -48 to 48; signed values are supported.
- Fine shift (cents): Measured or assumed numerical value, from -100 to 100; signed values are supported.
- Original reference frequency (Hz): Measured or assumed numerical value, from 1 to 100000; must be positive.
- Original duration (seconds): Measured or assumed numerical value, from 0 to 1000000; zero is supported where the stated method permits it.
Worked example with answer
A +12-semitone, 0-cent speed change has a 2x ratio. A 220 Hz tone becomes 440 Hz; a 30-second clip becomes 15 seconds, a -15-second difference.
How to use the results
This distinguishes varispeed from pitch-shifting algorithms that preserve duration. Negative semitone and cent values are valid downward shifts.
Results retain full precision internally and display up to four decimal places. Very small nonzero results use scientific notation rather than appearing as zero. Check the labels before comparing values across units.
Limitations and references
Equal temperament is a mathematical convention, not a guarantee of an instrument's tuning. Time-stretching and formant preservation are not modeled.
The method is a self-contained arithmetic, geometric or explicitly stated mathematical model. There are no imported tariffs, empirical presets or equipment specifications; measured values and allowances must come from your own process.
Related planning tools
Creator & reviewers
Creator persona
- Casey RowanUnits, conversions & measurement
Reviewer personas
- Devon ShawFormula & assumptions review
- Sage MitchellClarity & usability review