Biorhythm Calculator
Chart your physical, emotional, and intellectual cycles for any day.
Your Details
Try today, an exam day, or any important date.
Enter your date of birth to calculate your biorhythm.
How this calculator works
- Each cycle value = sin(2ฯ ร days-alive รท cycle length), from -100% to +100%.
- Physical = 23-day, emotional = 28-day, intellectual = 33-day cycle, all starting at birth.
- A "critical day" is when a cycle crosses zero (the least stable point).
- All math runs in your browser โ no data is sent to or stored on a server.
- For entertainment and reference only; biorhythm is not scientifically proven.
The Three Cycles
Biorhythm theory proposes that from the day you are born, three cycles rise and fall like waves. When a wave is in its high (positive) half you tend to feel strong in that area; in the low (negative) half you recharge. The day a wave crosses the middle line is called a critical day.
๐ช Physical โ 23 days
Strength, stamina, coordination, and overall energy. Handy to glance at before a workout, sports event, or physically demanding day.
๐ Emotional โ 28 days
Mood, sensitivity, and creativity. Often watched around big conversations, dates, or creative work.
๐ง Intellectual โ 33 days
Focus, memory, logic, and judgment. Some people check it before exams, interviews, or big decisions.
Frequently Asked Questions
Each cycle is a sine wave that starts at zero on the day you were born. Its value on any day equals sin(2ฯ ร days-alive รท cycle length), shown here as a percentage from -100% to +100%. The physical cycle repeats every 23 days, emotional every 28 days, and intellectual every 33 days.
A critical day is when a cycle crosses the zero line โ switching from the high (positive) half to the low (negative) half, or vice versa. On these transition days the cycle is considered least stable, so caution is often advised.
No. Biorhythm theory is not supported by scientific evidence and controlled studies have found no predictive value. This tool is provided for entertainment and self-reflection only โ not as medical, psychological, or decision-making advice.
The physical cycle (23 days) reflects strength, energy, and endurance; the emotional cycle (28 days) reflects mood, sensitivity, and creativity; and the intellectual cycle (33 days) reflects focus, memory, and judgment. High values suggest a peak, low values a recharge phase.