P
Period Calculator
Next period dates from last period and cycle length.
Next period
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Expected end
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Period after that
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Estimate your next period dates
Use this free period calculator online to estimate the next period from the first day of your last period and your cycle length.
The page adds your cycle length to that start date. The expected end assumes a 5-day period. This is a calendar estimate, not medical advice.
Irregular cycles can shift the real dates. For ovulation timing, use the Ovulation Calculator.
period calculator FAQ
How do I use this period calculator?
Enter the first day of your last period and your usual cycle length in days. The next period start, expected end, and the period after that appear on the right.
Is the period calculator free?
Yes. You can use this period calculator online free with no account.
Does this save my dates?
No. Dates stay in your browser.
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