Published by PitchChanger · Updated · How these guides are made
How to use this workflow
Choose the reference
Keep the target frequency in the denominator. Do not compare readings from different notes or unstable attacks.
Use a base-two logarithm
If your calculator has only natural log, use 1200 × ln(measured/reference) / ln(2).
Interpret the result
Compare the sign and magnitude with the intended target; do not infer a tuning fault from one fluctuating reading.
A 442 Hz reading against 440 Hz
1200 × log2(442/440) = +7.851 cents. Reversing the inputs gives −7.851 cents. The 2 Hz difference alone does not describe the musical interval.
For comparison, 222 Hz against 220 Hz is +15.667 cents: the same absolute 2 Hz gap creates almost twice the interval at this lower reference. These are calculated inputs, not microphone tests.
Swipe or scroll sideways to read all columns.
| Measured / reference | Difference in Hz | Calculated cents |
|---|---|---|
| 442 / 440 | +2 | +7.851 |
| 222 / 220 | +2 | +15.667 |
| 438 / 440 | −2 | −7.887 |
| 880 / 440 | +440 | +1200 |
Avoid octave and sign mistakes
A doubled frequency is +1200 cents even when both readings share a note name. Confirm the octave before using cents to tune a string. A harmonic mistaken for the fundamental can produce a mathematically correct interval for the wrong sound.
Guitar Tuner displays cents relative to its current target. It does not accept two typed frequencies. Use this formula for an independent check and the actual tuner for a stable single-note reading. Pitch Changer has whole-semitone controls, so a +7.851-cent correction is not an available edit.