Semitone Interval Calculator
Measure the interval between two frequencies in semitones and cents, and name it.
A semitone is 100 cents, and an octave is exactly 1200. Feed in two pitches — say a note and the one you're tuning against — and this tells you how far apart they sit and which interval that gap forms.
How it works
The pitch gap between two frequencies is measured in cents: 1200 × log2(f2 / f1). Because our ears hear pitch on a ratio scale, doubling the frequency always adds the same 1200 cents — one octave — no matter where you start.
There are 100 cents in a semitone, so dividing the cents by 100 gives you the distance in semitones. A perfect fifth, like 440 Hz up to 660 Hz, works out to about 702 cents, or just over seven semitones.
The tool rounds the semitone count to the nearest step and looks up the matching interval name — minor third, perfect fifth, octave, and so on — while still showing the exact cents so you can spot anything slightly out of tune.
Frequently asked questions
What is a cent in music?
A cent is one hundredth of a semitone, giving 1200 cents to an octave. It's the standard fine unit for tuning — most people start to notice pitch differences around five cents.
Why use a logarithm to measure intervals?
Pitch perception is based on frequency ratios, not differences. A logarithm turns those ratios into an even scale, so equal musical steps come out as equal numbers of cents.
How many cents is a perfect fifth?
A pure (just) fifth is about 702 cents, while equal temperament rounds it to exactly 700. That two-cent gap is why tuning systems are always a bit of a compromise.