Biorhythm
Your physical, emotional and mental cycles today — a modern rhythm model, not a traditional reading.
What draws these three curves — one number, and nothing else
This screen reads a single thing: how many days have passed since the day you were born. Call that number d. Each of the 3 curves is the same sine wave measured against its own period, so the value you see is 100 × sin(2π × d / period) rounded to a whole number, and it always sits between −100 and +100. The three periods are 23·28·33 days.
| Curve | Period (days) | Value on day d |
|---|---|---|
| Physical (energy & condition) | 23 | 100 × sin(2π × d / 23) |
| Emotional (mood, relationships) | 28 | 100 × sin(2π × d / 28) |
| Intellectual (focus & judgment) | 33 | 100 × sin(2π × d / 33) |
On the day you were born d is 0, so all three curves start at exactly 0 and rise from there. Nothing else enters the calculation. Two people born on the same date see the same three numbers today, wherever they are and whoever they are, and this screen does not pretend otherwise.
Because 23·28·33 have no common factor beyond 1, the three curves only come back to that starting position together after 21,252 days — about 58.2 years. Most lives hold one such return; almost no one lives to see a second.
How a number becomes a sentence
The bar is a number; the line under it is one of 4 fixed phrases. The cut points never move and they do not depend on who you are — the same value always produces the same sentence.
| Value | The line you get | Days out of 23·28·33 |
|---|---|---|
| +60 … +100 | peak — make the most of it. | 7·9·10 |
| +15 … +59 | good — things flow. | 3·4·5 |
| −14 … +14 | a turning point — go easy and check in. | 3·2·3 |
| −100 … −15 | low — conserve and rest. | 10·13·15 |
Those 4 bands do not divide the scale evenly, and it is worth saying so plainly. The top band covers 41 of the possible values while the bottom one covers 86. Counted over one full turn of each cycle, the low phrase lands on 10·13·15 days against 7·9·10 for the peak one. A low reading is the ordinary case here, not a warning about your day.
One thing this page owes you. Biorhythm is not a tradition. It was assembled in the late 19th and early 20th century — Wilhelm Fliess, Hermann Swoboda, and later Alfred Teltscher — and became popular in the 1970s. It has no connection to Saju, to the I Ching, or to any older lineage, and controlled studies that looked for predictive power did not find it. We keep it as a gentle daily mirror, a prompt to check in with yourself, and we do not claim it predicts anything.
So this screen asks for a date and nothing more. It does not know your birth hour, your sex, your name or where you live, and no sentence here assumes any of them.
How the biorhythm chart is calculated — and what it isn't
Three sine curves — physical (23-day), emotional (28-day), intellectual (33-day) — from the number of days since your birth date.
Each cycle is a simple sine wave: sin(2π × days-since-birth ÷ cycle-length), computed exactly for whichever day you're viewing.
Biorhythm is NOT part of Saju or any traditional divination lineage — it's a late-19th/20th-century idea popularized in the 1970s, and controlled studies have found no predictive validity. We keep it only as a gentle daily-mood mirror, clearly labeled as a modern model.
About the biorhythm chart
No, and we say so plainly: biorhythm has no connection to Saju, Zi Wei, or any classical divination lineage. It's a 20th-century Western construct with no scientific predictive validity.
As a light daily mood prompt, not a prediction. The three-cycle math is calculated correctly and honestly; we just don't claim it forecasts anything.