Biorhythm Calculator
Plot the physical, emotional and intellectual biorhythm cycles for any date.
Last updated · View algorithm, constants and default inputs (JSON)
This entertainment model plots three traditional sine waves from a birth date: 23 days (physical), 28 days (emotional) and 33 days (intellectual). These cycles are not validated forecasts of health, mood or performance. Do not use them for safety, medical or important personal decisions.
About this calculator
This entertainment model plots three traditional sine waves from a birth date: 23 days (physical), 28 days (emotional) and 33 days (intellectual). These cycles are not validated forecasts of health, mood or performance. Do not use them for safety, medical or important personal decisions.
Worked example
calculated with the default values below
Date of birth 1990-01-01 · Date to check 2026-10-31 Physical cycle -73.1 % · Emotional cycle 43.4 % · Intellectual cycle -75.6 % · Days since birth 13,452 days · Overall average -35.1 % · Physical phase Low
General background references
Disclaimer
These calculators give general estimates. Sizing, pricing, availability and standards vary by brand, retailer and country, so treat the output as a starting point and confirm it against the seller's or authority's own figures.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
P = 100·sin(2πd/23), E = 100·sin(2πd/28), I = 100·sin(2πd/33)
- d
- Days since birth
- P
- Physical cycle (%)
- E
- Emotional cycle (%)
- I
- Intellectual cycle (%)
Overall = (P + E + I)/3; the physical phase is flagged critical within ±5 of zero; cycle lengths are 23, 28 and 33 days.
Frequently asked questions
Can biorhythm cycles predict my health, mood or performance?
No. The chart applies fixed 23-, 28- and 33-day sine cycles from a birth date. These traditional cycles are not validated forecasts of health, mood or ability; treat the results as entertainment, not evidence or advice.