Biorhythm Calculator
By using our calculators, you agree to our Terms of Use.
For entertainment and self-reflection only. Not scientific, medical, financial, or relationship advice.
Sine-wave cycles (23 / 28 / 33 days) from birth date to a target day — classic curiosity chart, not medical science.
Birth & target date
Physical cycle
-40%
Emotional -62% · Intellectual -76%
- Emotional cycle
- -62%
- Intellectual cycle
- -76%
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How biorhythm curves work
Biorhythm theory plots three repeating cycles from birth: physical (23 days), emotional (28 days), and intellectual (33 days). Each cycle is a sine wave between +100 and −100, so “high” and “low” days are relative to the formula — not measured biology.
The idea became popular in the 1970s as a planning curiosity. No clinical evidence supports using biorhythms for health or performance decisions. Treat results as entertainment alongside the disclaimer on this page.
Example: on a target date 10,000 days after birth, each cycle is at a different phase — the calculator shows all three percentages so you can compare curves, not predict outcomes.
Common questions
Are biorhythms scientifically proven?
No. Mainstream science does not support biorhythm forecasting. This tool implements the classic formula for curiosity only.
Is this medical advice?
No. Do not use biorhythm output for health, fitness, or treatment decisions. Consult qualified professionals for medical questions.