Conception Date Calculator
Estimate your date of conception, ovulation window, and fertile period from LMP or due date.
Calculate From
Last Menstrual Period (LMP)
Expected Due Date (EDD)
Average menstrual cycle is 28 days. Adjust if yours differs.
Estimated Conception Date
Saturday, 7 February 2026
This is an estimate — actual conception can occur 1–5 days after ovulation
Fertility Timeline
Fertile Window Starts
5 days before ovulation
Monday, 2 February 2026
Ovulation Day
Egg released — highest fertility
Saturday, 7 February 2026
Fertile Window Ends
1 day after ovulation
Sunday, 8 February 2026
Implantation Window
6–12 days after ovulation
Monday, 16 February 2026
Estimated Due Date
40 weeks from LMP
Saturday, 31 October 2026
About Conception Date Calculator
How conception happens
Conception occurs when a sperm fertilises an egg. The egg is viable for only 12–24 hours after ovulation, but sperm can survive up to 5 days in the reproductive tract. This creates a fertile window of approximately 6 days — 5 days before ovulation and the day of ovulation itself.
Calculating ovulation from LMP
Ovulation typically occurs 14 days before your NEXT period
For a 28-day cycle: ovulation on Day 14 from LMP
For a 30-day cycle: ovulation on Day 16
For a 26-day cycle: ovulation on Day 12
Irregular cycles make prediction less accurate
Signs of ovulation
Light mittelschmerz (one-sided cramp)
Cervical mucus becomes clear and stretchy (egg-white)
Slight basal body temperature rise (0.2–0.5°C)
LH surge detectable with OPK (ovulation predictor kit)
Mild breast tenderness or bloating
🔒 All calculations happen in your browser — no data is sent to any server. Results are for informational purposes only.