Biorhythm Calculator


X Day ()


Biorhythm Calculator

Author: Alexandru Iuga (@lastunicorn)

GitHub page: here

Current features

  • Biorhythm charts for one person based on the birthday.
  • Possibility to select different color for biorhythms.
  • Percentage values of the biorhythms displayed for the X day.
  • Birthday saved in a cookie for later visits of the page.
  • Options panel to select different other biorhythms (secondary, extra and I-Ching).

Future features

  • Calculate and display compatibility between two persons.
  • Save the options in cookies.

According to believers in biorhythms, a person's life is influenced by rhythmic biological cycles that affect one's ability in various domains, such as mental, physical and emotional activity.

These cycles begin at birth and oscillate in a steady (sine wave) fashion throughout life; thus, by modeling them mathematically, a person's level of ability in each of these domains can be predicted from day to day.

Read more on Wikipedia.

A list of javascript libraries that helped me in my quest:

Biorhythm Charts

The biorhythm's chart displays the four primary biorhythms.


Drag the chart left or right using the left mouse button or use the mouse wheel to scroll.

The X Day

The black rectangle that marks one of the days in the chart is called the X day.

You can change the X day by dragging it with the right mouse button or by holding the Ctrl key and dragging it with the left mouse button.

The Legend

At the bottom-right of the chart a legend can be found, containing the names and the colors of the displayed biorhythms.

Change Color

By clicking the color square or the labels, the color used to draw the corresponding biorhythm in the chart can be changed.

The first and last days

At the top-left and top-right of the chart are two labels with the first and last day displayed in the chart.

Change the first or last days

Clicking on the labels, a date picker is displayed to modify the corresponding value. The other value will be modified accordingly. The chart will always display the biorhythm's charts for a range of 30 days.

The first and last days can also be modified by scrolling or dragging the chart right/left.

Birthday text box

The birthday can be changed by clicking the text-box bellow the biorhythm's cahrt. A date picker will be displayed to help choosing another birthday.

The "Save" button

Next to the birthday text-box a "Save" button will become enabled immediatelly after changing the birthday. If clicked it will save the currently used birthday in a cookie as default.

The "Reset" button

The second button displayed next to the birthday text-box is the "Reset" button that will set as current birthday the birthday currently existing in the cookie.

The X Day info section

Bellow the chart a section exists that shows the current values (as percentages) of the displayed biorhythms for the X day.