What is a normal cycle length?
A normal menstrual cycle lasts between 21 and 35 days, with the average being about 28 days. Cycles outside this range aren't necessarily a cause for concern, but consistently very short or very long cycles are worth discussing with a healthcare provider.
Why does my cycle length change?
Cycle length can vary due to stress, changes in sleep or exercise, travel, illness, weight changes, or hormonal shifts. It's normal for cycles to fluctuate by a few days from month to month. Significant or sudden changes may be worth tracking and mentioning to your doctor.
How many periods do I need to track?
At minimum, enter 3 period start dates (which gives you 2 cycle lengths to average). For best results, enter 6 or more dates - this gives a more reliable average and a clearer picture of your range.
Does cycle length affect fertility?
Yes. Knowing your cycle length helps predict when you ovulate. Ovulation typically occurs about 14 days before your next period. If your cycle is 28 days, ovulation is around day 14; if it's 32 days, ovulation is around day 18. Use our ovulation calculator for more detail.
