Pregnancy Conception Calculator
Estimates conception week by subtracting 2 from gestational week. Conception occurs approximately 2 weeks after LMP.
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How It Works
Estimates conception week by subtracting 2 from gestational week. Conception occurs approximately 2 weeks after LMP.
Quick Reference
Week 1
LMP week 1
Not yet pregnant
Week 2
Ovulation week
Conception occurs
Week 4
Implantation
Pregnancy hormone rises
Tips & Shortcuts
Most accurate: ovulation tracking or early ultrasound.
Implantation occurs 6-12 days after fertilization.
Common Mistakes
Confusing fertilization with implantation date
Fertilization at ovulation. Implantation 6-12 days later.
Using for precise paternity timing
Sperm survive 3-5 days creating multi-day window.
Frequently Asked Questions
Conception occurs at fertilization, 12–24 hours after ovulation. Since sperm survive 3–5 days, intercourse up to 5 days before ovulation can lead to conception.
Yes. Subtract 266 days from your due date for the estimated conception date. The actual window spans about 5–7 days due to ovulation variability.
Ovulation timing varies even in regular cycles. A first-trimester ultrasound at 10–13 weeks is the most accurate dating method.
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