Biorhythm Compatibility Calculator

This novelty tool runs the classic biorhythm sine waves for two birth dates on the same target day, then scores how closely the three percentages align. A higher score means the physical, emotional, and intellectual numbers are nearer each other — arithmetic similarity, not relationship chemistry or longevity prediction.

1970s magazine pages sold "compatibility" charts for couples comparing wedding dates or birthdays. The tier labels (Harmonious, Balanced, Challenging) are cosmetic buckets on the score — fun for party conversation, not input to life decisions.

Defaults: Person A born January 15, 1990; Person B born August 20, 1992; target August 7, 2026. Change the target to an anniversary or trip date to see how the score moves; different days produce different alignment because each person's cycles drift independently.

Common mistakes include treating a low score as relationship doom, comparing compatibility on one day as permanent trait, and sharing results with someone who believes the system is scientific.

Compare scores across multiple candidate dates — wedding planners curious about the novelty might run August 7 versus August 8 to see score jitter without treating either as advice.

Same-sex and opposite-sex pairs use identical math — the formula has no gender inputs; only birth dates and target day matter.

Long-distance couples comparing "today" scores should use the same target date in both time zones — date-only input avoids clock confusion.

Team-building icebreakers sometimes use compatibility scores for laughs — debrief that the tier label is not HR guidance.

Compatibility with a pet or fictional character birth dates is mathematically valid but nonsense contextually — entertainment limits apply.

Score differences of a few points between adjacent days are normal — do not over-interpret small swings as relationship verdicts.

Limits: entertainment only — not relationship counseling, medical, or psychological guidance. Real compatibility involves communication, values, and context no sine wave captures.