[header] How to keep a menstrual calendar [title] Get a calendar suitable to your needs. [step] There are currently many different calendar options to track your cycle. You can choose to keep a physical calendar or journal or take advantage of any number of online tools or smartphone apps to track your menstrual cycle. 
Figure out which type best suits your needs and wishes. [substeps] Buy a paper calendar with plenty of space to make notes if you want to document your cycle by hand.