Octave Calculator
Calculate the octave and frequency ratio between two audio frequencies, or find a note an octave up or down, with this free calculator.
Enter Values
Minimum 0
Minimum 0
How to use this calculator
- Enter the two frequencies.
- Read the octaves and cents apart.
How it works
Octaves = log₂(frequency 2 ÷ frequency 1); one octave = 1200 cents.
Worked example
440 Hz to 880 Hz. = 1 octave (1200 cents).
Common mistakes
- Thinking an octave is a fixed number of hertz — it's a doubling ratio.
- Swapping the two frequencies (gives a negative result).
Frequently asked questions
What is an octave in frequency terms?
A doubling or halving of frequency — 440 Hz up an octave is 880 Hz, down an octave is 220 Hz.
How many semitones are in an octave?
Twelve equal semitones; each multiplies frequency by 2^(1/12), and twelve of them double it.
What's a cent?
1/100th of a semitone, or 1/1200th of an octave — the standard fine measure of pitch difference.
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Cite this tool
Zerdly. (2026). Octave Calculator. Retrieved from https://www.zerdly.com/tools/octave-calculator/
Tip: Enter any known values to calculate the remaining results.
Designed to run locally in your browser. Tool inputs are not intentionally stored by Zerdly unless stated otherwise.