Ovulation Calculator
Estimates your most probable ovulation date and fertile window from the first day of your last period and average cycle length, plus your next period date and where you are in the current cycle.
TheCalculators — Ovulation Calculator
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Estimated Ovulation Date
November 22, 2026
Fertile window Nov 17, 2026 – Nov 23, 2026
- Ovulation date
- November 22, 2026
- Fertile window
- Nov 17, 2026 – Nov 23, 2026
- Best days to conceive
- Nov 21, 2026 – Nov 23, 2026
- Next period expected
- December 6, 2026
- Today
- Cycle day 1 — Follicular phase
- Cycle length used
- 28 days
Fertile window detail
Day 10-18 is typically the most fertile phase of a 28-day cycle.
This calculator should not be used as a form of birth control — cycles vary between and within women. Estimates for informational purposes only — not medical advice.
Most useful next
Formula
Ovulation ≈ first day of next period − 14 days · Next period = LMP + cycle length
- • Add your average cycle length to the first day of the last period to get the next period.
- • Subtract 14 days to estimate ovulation (the luteal phase is fairly fixed).
- • Sperm survive up to 5 days, so the fertile window opens 5 days before ovulation.
Pro tips
- • Basal body temperature rises about ½-1 °F after ovulation — charting confirms the estimate.
- • LH ovulation kits detect the hormone surge 24-48 hours before ovulation.
FAQ
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