Conception Calculator
Estimate conception date
Formula
Conception ≈ Due Date - 266 days
Or: LMP + 14 days (average)
Key Dates
| Ovulation | ~Day 14 |
| Implantation | 6-12 days later |
| Test positive | ~Day 28+ |
Related
Complete Guide to Conception Calculator
Conception typically occurs during ovulation, about 14 days after the first day of your last menstrual period. This calculator estimates your conception date based on your due date.
Understanding Conception
The fertile window spans about 6 days. Sperm can survive up to 5 days, while an egg is viable for 12-24 hours. Conception occurs when sperm meets egg in the fallopian tube.
Why It Is An Estimate
- Ovulation timing varies between cycles
- Sperm can survive several days
- Sex may occur days before fertilization
Frequently Asked Questions
Conception is estimated as 266 days before your due date, or about 14 days after LMP. The exact date depends on when you ovulated.
Not precisely. The fertile window spans several days, and sperm can survive up to 5 days, so conception could occur days after intercourse.
Sperm can live up to 5 days. Sex on Monday could result in conception on Friday if that is when ovulation occurred.
No. Conception (fertilization) happens in the fallopian tube. Implantation occurs 6-12 days later when the embryo attaches to the uterus.
It provides an estimate within a 6-day window. Individual variation in ovulation means the actual date could differ by several days.
Not definitively. The fertile window spans several days. DNA testing is required for certainty about paternity.
Gestational age counts from LMP (about 2 weeks before conception). Fetal age counts from actual conception, so it is always 2 weeks less.