Period Calculator
Predict your next period date from your last period and average cycle length.
Predicting your next period uses your last period's start date and your average cycle length — useful for planning ahead, though actual timing can vary cycle to cycle.
Why predictions get less reliable with irregular cycles
This works best with a fairly consistent cycle length — if your cycles vary significantly month to month, predictions become less reliable, and a period-tracking app that learns your personal pattern over several months may give better accuracy.
Frequently asked questions
What's considered a normal cycle length?
Cycles between about 21 and 35 days are generally considered typical, though what's normal varies by individual.
Should I see a doctor about irregular cycles?
If your cycles are consistently unpredictable or you have other concerns, it's worth discussing with a healthcare provider rather than relying on prediction tools alone.