Print the picture of the pregnancy wheel twice (in Windows: right-click on it, click `print`)
Cut out a circle on your first copy, follow the RED circle.
Pin the small circle you just cut out on the other copy.
How to use it
Turn the wheel so that the blue arrow (Last menstrual cycle) points at the date of -you guessed it- your last menstrual cycle
If your period is 4 days longer than the average 28 days, your conception is probably 2 days later. turn the wheel 2 days clockwise.
If your period is 6 days shorter than the average 28 days, your conception is probably 3 days earlier. turn the wheel 3 days anti-clockwise.
Look at todays date, (
) draw an imaginary line to the middle of the wheel.