Ovulation Calculator
The Ovulation Calculator estimates your most fertile days, ovulation date, next period, and an estimated due date if you conceive — based on the first day of your last period and your average cycle length.
Enter the first day of your last period to see your fertile window.
Ovulation is estimated as roughly 14 days before your next period, with the fertile window covering the 5 days before through the day after. Cycles vary, so this is an estimate, not medical advice or contraception. Nothing is uploaded.
How This Tool Works
Pick the first day of your last period and enter your average cycle length. You’ll see your fertile window, estimated ovulation day, next period date, and an estimated due date if you conceive.
Formula & Method
Ovulation is estimated at about 14 days before your next expected period (cycle length − 14). The fertile window spans the 5 days before ovulation through the day after, when conception is most likely.
Example Calculation
With a 28-day cycle starting on the 1st, ovulation is estimated around the 15th, and the most fertile days run from about the 10th through the 16th.
Frequently Asked Questions
How is the fertile window calculated?+
It’s the 5 days before ovulation plus the day after — sperm can survive several days, so intercourse in this window gives the best chance of conception.
Can I use this to avoid pregnancy?+
No — cycle timing is only an estimate and ovulation can shift, so this is not a reliable form of contraception. Talk to a healthcare provider about birth control.
Is my information private?+
Yes — all dates are calculated in your browser and nothing is uploaded or stored.
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<a href="https://everyfix.net/tools/ovulation-calculator/">Ovulation Calculator</a> by <a href="https://everyfix.net">EveryFix</a>Related Tools
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