Biorhythm
Biorhythm — runs in your browser. Inputs are not stored.
Biorhythm
Enter values, then press Calculate.
Classic biorhythm (sine cycles), for reference. Not a scientifically established measure.
How to use
- Pick a date of birth on the calendar. Calculation does not run if it is empty.
- As-of date (today if blank) is filled with today when the page opens. Change it to view another day.
- Press Calculate for elapsed days, physical (23-day), emotional (28-day), and intellectual (33-day) percentages, bars, and a chart.
- The chart centers a dashed line on the as-of date and draws three curves for about 30 days before and after. Colors are physical, emotional, and intellectual.
- Numbers show the sine cycle as a percentage near −100% to 100%. They are not medical values or fortune scores.
- Reset hides the birth date and result area. The as-of date may remain, so set it back to today if needed.
Key concepts
Classic biorhythm is an entertainment formula that lays 23-day physical, 28-day emotional, and 33-day intellectual sine waves on days since birth. It is not a scientifically accepted predictor of health, mood, or intelligence. This page only draws that formula.
Values are sin(2π × elapsed days / period) turned into a percentage for reference. Do not use them to judge clinic visits, workout intensity, or exam results. For entertainment/reference only; for age, use the age calculator. A rising or falling curve is only sine position—it does not mean condition, luck, or odds of passing. Do not read it with lab numbers, psych tests, or horoscopes.
Example
Enter 1 May 1990 as the birth date and today as the as-of date, then calculate to see elapsed days, three percentages, bars, and curves. A curve above the center dashed line only means that cycle is in a positive stretch, not that you are medically “in good shape.” Treat it as fun. Put tomorrow in the as-of date to draw tomorrow’s three indicators for reference only. Do not change plans from those numbers; compare them for amusement.
Related: age calculator · D-day calculator · countdown timer
Frequently asked questions
Does the biorhythm calculator predict health?
No. It is an entertainment sine cycle for reference only. Do not use it for medical judgment, diagnosis, or treatment.
What are the physical, emotional, and intellectual biorhythm cycles?
They are 23-, 28-, and 33-day cycles borrowed from a classic formula. They are not an established scientific biological clock.
What if I leave the biorhythm as-of date blank?
Calculation treats it as today. The as-of field is often pre-filled with today when you open the page.
What is the dashed line in the middle of the biorhythm chart?
The as-of date. The left shows about 30 past days; the right shows about 30 days ahead.
Are biorhythm results saved?
No. The birth date is calculated only in the browser and is not sent to a server.
Can I see international age together with biorhythm?
This screen has no age. Use the age calculator for age and the D-day calculator for date differences.
Last reviewed: 2026-09-04