Biorhythm calculator

Your biorhythms

Day of life: | Date:

What are biorhythms?

Biorhythm theory suggests that from the moment of birth a person's life is governed by three sinusoidal cycles of fixed length. Each cycle starts at zero on your birthday, rises to a peak, returns to zero at the midpoint, drops to a low, then returns to zero again, completing the cycle.

• Physical cycle (23 days) — governs physical energy, strength, endurance, coordination and immunity. Peak — days of athletic records; low — illness and fatigue are more likely.
• Emotional cycle (28 days) — governs mood, sensitivity, creativity and emotional stability. It aligns with the lunar cycle.
• Intellectual cycle (33 days) — governs thinking, memory, concentration and learning ability. Important for exams, negotiations and decisions.

Positive phase (+) — a period of uplift and peak effectiveness. Negative phase (−) — a period of recovery. Critical days (crossing 0) — moments of instability that call for extra caution.

History of the theory

The concept of biorhythms emerged in the late 19th century. The Berlin otolaryngologist Wilhelm Fliess noticed 23- and 28-day periodicities in patients' conditions. Later the Austrian psychologist Hermann Swoboda confirmed the same cycles in his clients. In the 1920s Alfred Teltscher — an engineer from Innsbruck — identified a third, 33-day intellectual cycle while observing student performance.

How to use the chart

1. Schedule competitions and heavy physical activity for the peak of the physical cycle (+).
2. Important conversations and presentations — on the upswing of the emotional cycle.
3. Exams, strategic decisions and learning new things — at the peak of the intellectual cycle.
4. Double/triple critical days are a good reason to rest and avoid making important decisions.

Connection with astrology

Biorhythms are a system independent of astrology, but both see a person as part of a cyclical universe. Unlike transits and progressions, where planetary motion sets the rhythm, biorhythms rely only on the exact date of birth. Combining the two approaches gives a fuller picture of peaks and troughs: an astrological transit can amplify or soften a biorhythm phase.

Biorhythm theory lacks strict scientific confirmation and belongs to popular psychology. Use it as an additional tool for self-observation.