myBiorhythm lets you visualize the Biorhythm for a given Birthday for Today or at any given Date. It has an Overview of the best and worst Days for the selected Year and also show's you the Percentage and the Icons on your Apple Watch as App or Complication.
In Landscape Mode you can see an increased Graph with more days.
The additional Database Module allows you to store a multitude of different Birthdays and to swap between them quickly and easily just by 'selecting' which one has to be active. The Group Module lets you create Group of Persons and see their curves as a median value and the current day for each person at a glance.

According to the theory of Biorhythms, a person's life is influenced by rhythmic biological cycles that affect his or her ability in various domains, such as mental, physical and emotional activity. These cycles begin at birth and oscillate in a steady fashion throughout life, and by modeling them mathematically, it is suggested that a person's level of ability in each of these domains can be predicted from day to day. The theory is built on the idea that the biofeedback chemical and hormonal secretion functions within the body could show a sinusoidal behavior over time.

The free Version only offers the primary Values, via InApp Purchase you can upgrade to the full version and benefit from additional Values plus the combined Line and another View that shows you the best and worst Days of the Year.