Calculate your biorhythm

The free online biorhythm calculator app

Calculate your biorhythm online for free!

MM/DD/YYYY - z.B. 03/26/2014
MM/DD/YYYY - z.B. 03/26/2014
MM/DD/YYYY - e.g. 05/28/2024

Your biorhythm

Have you ever asked yourself why you are in top form on certain days and why you succeed in everything you do? Or what could be the trigger for those days when nothing goes as it should? Your biorhythm - your inner clock could give you information about it! Here you can calculate your personal biorhythm online for free on any date.

Take your own biorhythm into account and pay attention to your "good" and "bad" phases. Do not burden yourself with the most difficult tasks in periods when you are doing well to regenerate. Use the good times for tasks that really challenge you. Everything has its time!

The scientific basis of biorhythm calculation can be found in chronobiology. There, human time cycles are scientifically examined and both personal and overarching patterns and rhythms are determined.


The basis for the biorhythm was laid at the beginning of the 20th century by the Viennese psychologist Hermann Swoboda and the Berlin physician Wilhelm Fliess. Fliess believed that he had discovered consistent regularities in the medical records of his patients and formulated a derivation as a period theory. Both tried to discover a regularity behind the "good" and "bad" moments of a life.

Read more about Swoboda & Fliess

Biorhythm: the cycles

Biorhythm is based on three rhythms with different cycle durations:

  • physical rhythm (23 days)
  • emotional rhythm (28 days)
  • intellectual rhythm (33 days)

At birth, these rhythms should start sinusoidally with their first period in a positive way (biorhythm diagram), cross the zero line after half a period length and then go into a negative phase (+/- 100). At the end of the period there is another change to the positive range and so the curves continue as repeating cycles.

Critical, potentially "bad", days are those transitions where there is a change from positive to negative and vice versa. If there is a transition of all three phases on the same day, this can have crisis-like consequences according to biorhythmic theory, and in contrast, the coincidence of positive days can result in particularly good days.