Biorhythm Compatibility: How Two Cycles Are Compared
Biorhythm compatibility compares two people's physical, emotional and intellectual curves to see how closely they move together. Because both people's rhythms use the same cycle lengths, the only thing that matters is the difference between their birth dates. Two people born a whole number of cycles apart move in perfect step for that rhythm; two people born half a cycle apart move in opposite directions.
The formula. For each rhythm, value = sin(2π × t / P) × 100, where t is the number of days since birth and P is the cycle length: 23 days (physical), 28 days (emotional) or 33 days (intellectual). The result runs from -100 to +100.
Step 1: find the offset
Count the days between the two birth dates (d), then take the remainder for each cycle: d mod 23, d mod 28 and d mod 33. A remainder of 0 means the curves are in step. A remainder of half the cycle (11.5, 14, 16.5) means they are exactly opposite.
Step 2: turn it into a percentage
There are a few formulas in use. A simple one is cos(2π × r / P), mapped from -1 to +1 onto 0% to 100%. Trisine uses a day-by-day version: for every day of one full cycle it takes both people's values a and b, scores the day as 100 - |a - b| / 2, and averages the scores. Curves that move together score 100%; curves in exactly opposite phase score about 36%.
Example
Two siblings born 1,000 days apart. Physical: 1,000 mod 23 = 11, almost half of 23, so their physical curves move nearly opposite. Emotional: 1,000 mod 28 = 20, which is 8 days from being in step. Intellectual: 1,000 mod 33 = 10, close to a third of a cycle apart. So their emotional and intellectual rhythms partly overlap, while their physical highs and lows rarely meet.
How to use it
Compatibility is a fun way to compare charts with a partner, friend or family member, for example to notice that one of you tends to have energy when the other wants a rest. It says nothing reliable about a relationship and should never be used to judge one.
Compare two people in one tap
In Trisine, add profiles for family and friends in the People tab, choose two people and see a match score for each rhythm, an overall score and both curves overlaid on one chart.
Biorhythms are a traditional calculation, not a scientific prediction or medical advice. Controlled studies have not found that they predict performance or accidents. Treat the chart as a prompt for reflection, and plan your day your own way.
FAQ
Does a low biorhythm compatibility mean we don't get along?
No. It only means two sine curves are out of step. How people get along depends on far more than birth dates.
Does compatibility change over time?
Barely. Because both curves have the same length, the gap between them stays fixed for life. Only the date window you average over changes, which shifts the score slightly.
Is there an app that compares biorhythms of two people?
Trisine compares any two profiles and shows a score per rhythm, an overall score and both curves overlaid.