How it works
A useful estimate, explained.
Cycle predictions add your usual cycle length to the first day of your last period. Real cycles commonly vary from month to month.
Source: ACOG menstrual health informationCycle healthMonthly
Period & Cycle Calculator
Plan ahead with a clearer view of your cycle.
Quick answer
See the next three estimated period start dates plus an approximate ovulation and fertile window.
Your result
Ready when you are.
Add your details and calculate to see an estimate with a clear explanation and useful supporting numbers.
FastInstant result
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Keep in mind
The number is not the whole story.
Do not use these dates as contraception or to diagnose fertility. Seek care for pregnancy concerns, severe symptoms, or major cycle changes.
Vitalo tools provide general education, not medical advice, diagnosis, or treatment.
Clear answers
Frequently asked questions
How does the Period & Cycle Calculator work?
Cycle predictions add your usual cycle length to the first day of your last period. Real cycles commonly vary from month to month.
What are the limits of this result?
Do not use these dates as contraception or to diagnose fertility. Seek care for pregnancy concerns, severe symptoms, or major cycle changes.
Is the Period & Cycle Calculator medical advice?
No. This free tool provides a general educational estimate and cannot diagnose a condition or replace advice from a qualified healthcare professional.
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