A biorhythm is based on the idea that certain aspects of your life move in cycles.
Humans go through the same sequence of energy levels for each cycle.
The measurements are based on the number of days we have lived. The top line where the date is will also tell you how many days you've lived. You'll notice that there are actually 6 lines, three of the lines are straight while the other three are curved. The curved ones are the accurate degrees while each straight line gives you the average on that corresponding color.