Biorhythm calculator
Calculate your three biorhythm cycles (physical, emotional, intellectual) on a given date, according to the theory popularized in the 19th and 20th centuries. This tool is purely for fun, with no recognized scientific basis, and runs entirely in your browser.
How it works
Biorhythm theory assumes that three regular sinusoidal cycles — 23 days for the physical, 28 days for the emotional, 33 days for the intellectual — begin at birth and repeat throughout life. This tool calculates the number of days elapsed since your birth up to the chosen date, then positions each cycle on its curve to get a percentage between -100% and +100%.
What do positive and negative values mean?
A value close to +100% corresponds, according to the theory, to a peak in the relevant cycle (for example optimal physical shape), while a value close to -100% corresponds to a trough. Values close to 0% mark transition days between the two, sometimes described as "critical" days in the literature on the subject.
Is biorhythm scientifically validated?
No, several studies conducted since the 1970s have found no statistical correlation between biorhythm cycles and real events (accidents, sports performance, etc.). This tool is offered purely for entertainment, with no scientific claim.
Your date of birth is only used locally, in your browser, and is never sent to a server.