What are the three cycles calculated by the tool?

The tool calculates the 23-day physical cycle, the 28-day emotional cycle, and the 33-day intellectual cycle.

What is a critical day in biorhythms?

A critical day occurs when a cycle curve crosses the zero line, transitioning between positive and negative phases, which theoretically represents instability.

Is biorhythm theory scientifically proven?

No, biorhythm theory is a historical hypothesis from the late 19th century and has no scientific validation.

Can I change the number of days displayed on the chart?

Yes, you can adjust the span of days to plot anywhere from 6 to 120 days using the span days option.

What does the combined total in the daily table represent?

It is the sum of the physical, emotional, and intellectual cycle values for that day, ranging from -300 to +300.

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Biorhythm Curve Plotter

Plot the classic 23-day physical, 28-day emotional, and 33-day intellectual biorhythm sine curves around any target date. See today's cycle states, mark zero-crossing "critical days", and read a daily value table with a combined total — enter your date of birth and a target date.

Details

What this tool helps you do

A biorhythm chart generator based on the classical three-cycle hypothesis:

Enter your date of birth and a target date (defaults to today).
The tool computes the three sine waves for physical (23d), emotional (28d), and intellectual (33d) cycles.
SVG chart — clean plot of all three curves around the target date with grid and date ticks.
Critical days — zero-crossings marked and listed.
Daily table — every day's values plus a combined total.

⚠️ Biorhythm theory is a historical curiosity and is not scientifically validated.

Execution

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Prepared example runs

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1 examples

30-day biorhythm around today

Plot the three cycles across 15 days before and after the target date, with critical-day markers and a daily value table.

<div class="bio-wrap"><svg class="bio-svg" viewBox="0 0 720 320">…three sine curves…</svg><table class="bio-today">…Physical / Emotional / Intellectual…</table></div>

Inputs

Set the required fields, then run the tool.

4 options

SettingsAdjust formats, ranges, numbers, and modes.4

Date of birthdateRequiredTarget date (today by default)dateOptionalChart rangeselectOptionalDays to plotnumberOptionalTotal days shown. In "around" mode this is split evenly before/after the target date.

Result

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Samples

Biorhythm Curve Plotter

What this tool helps you do

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Prepared example runs

Inputs

Result

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Key facts

Overview

When to use

How it works

Use cases

Examples

1. Plotting a 30-Day Biorhythm Around a Target Date

2. Checking Biorhythms for a Specific Birth Date

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