Why use cents instead of hertz?

Because a cent is the same proportional distance at every pitch. Ten hertz is a large interval low down and a tiny one high up, so a figure in hertz means different things in different registers, while a figure in cents always means the same musical distance.

How much is a cent in hertz?

It depends entirely on how high the note is, which is the point of the unit. Near the top of the piano a cent is a fraction of a hertz, and in the bass it is several, so the only way to answer the question is to ask at which frequency.

Why does the panel mention drift at five to ten cents?

Because that is roughly where a sustained tone starts to sound out of tune to a listener. Below it, most material passes as in tune; above it, the pitch becomes noticeable, and by around twenty cents a unison sounds clearly wrong to anybody listening.

What does the ratio column add?

Some controls are marked as a ratio rather than in cents, and a proportional shift applied to a set of frequencies is easier to express as a multiplier. The ratio and the cents figure describe the same relationship in two forms, so either can be used depending on what is being set.

Can I fix a recording that is a few cents sharp?

The arithmetic here tells you the ratio needed, which a pitch shifter can then apply as a very small shift. Shifts of only a few cents are well inside the range where time-domain processing is transparent, so the correction is usually inaudible as processing.

Cents Calculator

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Cents Calculator measures the distance between two frequencies in cents, and shifts a frequency by a given number of cents. It is the unit that tuning actually happens in.

What is Cents Calculator?

Use either panel: two frequencies give the interval between them in cents, or a frequency and a cents figure give the result of shifting by that amount.

The two panels:

An interval panel taking two frequencies, defaulting to four hundred and forty and four hundred and fifty, and reporting the difference in cents with its sign along with the ratio between them.
A shift panel taking a base frequency and a cents figure, defaulting to four hundred and forty hertz and a hundred cents, and reporting the resulting frequency and the ratio the shift represents.
A note stating that a hundred cents make a semitone, that twelve hundred make an octave, and that audible tuning drift starts somewhere around five to ten cents on a sustained tone.

The cent is a unit of proportion rather than of frequency, and that is exactly why it is used. Its size is defined so that any equal-tempered semitone is exactly a hundred of them at every pitch, which means a figure in cents describes the same musical distance whether it applies to a bass note or the top of a piano. The arithmetic behind the first panel takes the logarithm of the ratio between the two frequencies and scales it so that a doubling comes to twelve hundred, so the answer for four hundred and forty to four hundred and fifty comes out a little under forty cents. The second panel runs the same relationship backwards, raising the base frequency by the ratio that the cents figure implies, which is the calculation needed when a recording is known to be a fixed number of cents sharp and has to be corrected. The panel reports the ratio alongside for a practical reason: some equalisers, oscillators and detune controls are marked in ratios rather than in cents, and the ratio is also the figure needed if the same proportional shift has to be applied to a whole set of frequencies rather than to one. What the numbers cannot do is decide what matters. A few cents is inaudible on a single sustained tone and yet very audible between two instruments sounding together, so the threshold in the note is a guide rather than a rule.

Where the calculator stops:

It takes frequencies, so a measurement has to come from elsewhere.
No temperament other than equal is assumed.
The interval is reported as a signed difference, so an octave and its inverse are distinguished only by the sign.
No handling of beats or of two tones sounding simultaneously.
Nothing about how a given drift sounds on a particular instrument.
Nothing is uploaded, and no history is kept.

Use it when a tuning error has to be quantified, when a detune control marked in cents has to be translated into hertz, or when two readings need comparing. When the question is what note a frequency is rather than how far apart two of them are, the note frequency calculator and the frequency to MIDI note tool answer that, and when the interval has a musical name as well as a size, the interval calculator gives both.

How to use Cents Calculator

Enter two frequencies to read the interval between them in cents and as a ratio.
Or enter a base frequency and a cents figure to read the shifted frequency.
Use the ratio column when a control is marked in ratios rather than cents.
Compare the figure against the five to ten cent range where drift becomes audible.

When to use Cents Calculator vs related tools

Cents Calculator is the tool when a pitch difference has to be measured or applied in the unit that tuning works in, whether the source is a measurement or a specification. Note Frequency Calculator names notes rather than measuring distances, and Interval Calculator gives intervals their musical names. When the shift is going to be applied to audio rather than to a number, Pitch Shift Calculator works out what a change in speed would do to pitch.

Privacy & Security

This tool runs entirely in your browser — no data ever leaves your device. There is no server round-trip, no upload, no logging, and no account required. Your input is processed locally using client-side JavaScript and is never stored, transmitted, or accessible to anyone else. When you close the tab, everything disappears.