Donaldson R F Period Calculator
Predict your next few periods based on the first day of your last period and your average cycle length.
How this works
This projects your next few period start and end dates forward from your last period, using your average cycle length. Cycles naturally vary month to month, so treat these as estimates.
This is for general reference only, not medical advice. If your cycles are very irregular or you have concerns about your menstrual health, talk to a healthcare provider.