Conception (Fertilization) Date Calculator
Estimate the conception day from the LMP or the due date.
This tool is for informational purposes only and does not replace medical advice. Consult a doctor for decisions about your health.
days
Result
15 Ocak 2026
Estimated conception date: Thursday, 15 January 2026
Result in all units
Step-by-step solution
What Is the Conception Date?
The conception (fertilization) date is the estimated day the egg was fertilized. Fertilization usually occurs around ovulation, about two weeks after the last menstrual period.
How is it calculated?
How Is It Calculated?
- Enter your last menstrual period date.
- Estimated fertilization ≈ last period + 14 days (in a 28-day cycle).
- It can also be found by counting back 266 days from the estimated due date.
The result is an estimate; the exact date is determined by ultrasound.
Frequently Asked Questions
Is the conception date exact?
No; since the day of fertilization cannot be pinpointed exactly, medical follow-up is based on the last menstrual period date.