Conception Calculator
Ovulation typically occurs 14 days before the next period. Your fertile window spans 5 days before ovulation through ovu...
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How It Works
Ovulation typically occurs 14 days before the next period. Your fertile window spans 5 days before ovulation through ovulation day, because sperm survive 3–5 days. The highest probability days are the 2 days before ovulation and ovulation day itself.
Quick Reference
Day of ovulation
Peak fertility
~25% per cycle
1 day before
Highest probability
~33% per cycle
2 days before
High probability
~29% per cycle
5 days before
Lower probability
~10% per cycle
Tips & Shortcuts
Regular intercourse every 1–2 days throughout the fertile window maximizes conception chances without requiring precise timing.
Ovulation predictor kits (LH surge tests) detect the hormonal signal 24–36 hours before ovulation for more precise timing.
Basal body temperature (BBT) charting confirms ovulation after the fact — it helps identify patterns over multiple cycles.
Common Mistakes
Only having sex on the exact ovulation day
The egg is viable for only 12–24 hours. Having sex only on ovulation day risks missing the window entirely. Start 5 days before ovulation.
Assuming ovulation always occurs on day 14
Day 14 applies only to a 28-day cycle. Ovulation is always 14 days before the NEXT period, which varies by cycle length.
Frequently Asked Questions
The two days before ovulation and ovulation day itself have the highest conception probability — about 30% per cycle when intercourse occurs during this window.
Daily or every-other-day intercourse during the fertile window maximizes conception chances while maintaining sperm quality.
The fertile window spans 6 days: the 5 days before ovulation and ovulation day itself. Sperm survive 3–5 days in the reproductive tract.
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