This is a super common question for young females. Menstruation (or the process of having a period) usually starts after the age of 10, usually by the age of 14. For the first couple of years your period might come at random times. Sometimes bleeding will last for 3 days and start again in 2 weeks; other times it might last for 5 days and start again in 4 weeks. As annoying as it might be, it's normal for your period to take some time to be more on schedule. The best thing to do is always be prepared. Carry pads or tampons with you just in case it pops up when you least expect it.

Let's talk a little bit about what being "regular" means. Once your period is fully up and running on schedule, it will usually and predictably occur every 4 weeks or so. However, some women will have periods more frequently (like every 3 weeks) and others less frequently (like every 5 weeks). The number of days you bleed will also vary but is usually anywhere from 3 to 7 days. Everyone is different.

It's tempting to think your period comes at the start, middle or end of every month, but sooner or later the calendar will mislead you (as you know, not all months have the same number of days!). What's better to do is mark your period on a calendar (either on paper or in your phone). For a tutorial on how to track your period, check out the tools section.

If you have had your period for a few years but you are not yet quite regular, it's a good idea to talk with your doctor. You should know that this can still be totally normal, but there are a few other things that might be causing your funny flow. There are also things that a doctor can do to help make your period more regular, less painful and result in less blood loss.