Biorhythms by Date of Birth
Calculate your biorhythms online: physical, emotional and intellectual cycles for any date based on your birth date.
About the biorhythm calculator
The theory of biorhythms suggests that from the moment of birth three cyclic processes run in the body, influencing well-being, mood and mental activity. The calculator determines the phase of each cycle on a chosen date based on the number of days you have lived.
The physical cycle lasts 23 days and governs stamina, strength and energy. The emotional cycle spans 28 days and relates to mood, feelings and creativity. The intellectual cycle lasts 33 days and reflects clarity of thought, memory and analytical ability.
Each cycle follows a sine wave from +100% (peak) to −100% (low). The days when a value crosses zero are called critical — concentration may drop and fatigue can set in. The result is for entertainment and curiosity only and is not a medical prediction.
Benefits
Instant results
Just enter your date of birth and all three cycles are computed instantly in your browser, with no sign-up and no data sent to a server.
Any date
Calculate biorhythms not only for today but for past or future days — handy for planning important events ahead of time.
Clear charts
The physical, emotional and intellectual cycles are shown as colored bars with percentages and a high or low status.
Frequently asked questions
How do I calculate biorhythms by date of birth?
Enter your date of birth and the date you want to evaluate. The calculator works out how many days you have lived and shows the phase of the physical (23 days), emotional (28 days) and intellectual (33 days) cycles as a percentage.
What do the three biorhythm cycles mean?
The physical cycle (23 days) reflects energy and stamina, the emotional cycle (28 days) reflects mood and feelings, and the intellectual cycle (33 days) reflects clarity of thought and memory. Each rises and falls on its own schedule.
What is a critical biorhythm day?
A critical day is when a cycle value is close to zero and changes sign from plus to minus or vice versa. On such days the cycle is unstable, and performance may drop while fatigue increases.
What do the percentages in the result mean?
The percentage shows the current phase of a cycle: +100% is the peak, −100% is the lowest point, and near 0% is a critical transition. A value above 50% counts as high and below −50% as low.
Can I calculate biorhythms for a future date?
Yes. Set any future day in the target date field and the calculator will show the phase your cycles will be in. This is useful for planning competitions, exams or important meetings.
Are biorhythms scientific?
The theory of biorhythms is not strictly proven by science and belongs to popular psychology. Treat the results as a fun and informative reference, not as a medical or psychological diagnosis.