How to use this calculator
Convert a frequency into the nearest equal-tempered note, octave, and cents offset.
How the calculation works
- Enter a frequency in Hz.
- Choose the A4 tuning reference.
- The tool finds the nearest MIDI note and cents deviation.
Formula
MIDI = 69 + 12 x log2(frequency / tuning).
Example
440 Hz maps to A4 with 0 cents deviation when A4 is 440.
Understanding your result
Use the output as a practical starting point, then review it before using it in an important workflow.
Assumptions and limitations
- Input must be a positive frequency.
- Cents show how far the frequency is from the nearest note.
Frequently asked questions
Does this require an account?
No. The core tool works without creating a Tool2Do account.
Is my input included in share links or analytics?
No. Tool2Do share actions use the tool page URL and safe metadata, not private values or uploaded files.