Conception Calculator
Estimates the days with the highest probability of conception based on the first day of your last period and your average cycle length, plus the corresponding estimated due date.
TheCalculators — Conception Calculator
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Most Likely Conception Days
Nov 21, 2026 – Nov 23, 2026
Ovulation estimated for November 22, 2026
- Ovulation date
- November 22, 2026
- Fertile window
- Nov 17, 2026 – Nov 23, 2026
- Most fertile 3 days
- Nov 21, 2026 – Nov 23, 2026
- Next period expected
- December 6, 2026
- Estimated due date
- August 15, 2027
- Cycle length used
- 28 days
Fertile window day by day
Sperm survive up to 5 days in the body; the last 3 days of the window are the most fertile.
Cycles vary month to month — treat these dates as estimates, not a guarantee or contraception. Estimates for informational purposes only — not medical advice.
Most useful next
Formula
Ovulation ≈ LMP + (cycle length − 14) days · Due date ≈ LMP + 280 days (Naegele)
- • Count forward one full cycle from the first day of the last period to find the next period.
- • Ovulation falls about 14 days before the next period.
- • Intercourse from 5 days before ovulation through 1 day after gives the fertile window.
Pro tips
- • Regular lovemaking 2-3 times a week is the best preparation — no charting required.
- • Tracking basal body temperature and cervical mucus sharpens the estimate over a few cycles.
FAQ
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