Conception Calculator
Calculate best times for conception and fertility tracking. Free, fast, accurate — no signup, mobile-friendly, works in
Calculation Method
Date Information
Expected delivery date provided by your healthcare provider
Important Notes
- • Conception typically occurs during ovulation (14 days after LMP)
- • Sperm can survive 5 days, egg survives 24 hours
- • Due dates are estimates - only 5% of babies are born on their exact due date
- • These calculations are for educational purposes only
- • Consult your healthcare provider for medical advice
Calculate conception date from due date
Conception Date
Saturday, June 27, 2026
Most likely conception date
Conception Window
Earliest possible:6/22/2026
Most likely:6/27/2026
Latest possible:6/28/2026
Due Date
Saturday, March 20, 2027
Estimated delivery date (40 weeks)
Current Week
0w 0d
Gestational age
Trimester
1st
Current trimester
Fertility Window
Window starts:6/22/2026
Peak fertility:6/27/2026
Window ends:6/28/2026
The 6-day window when conception is most likely to occur
Fun Facts
Season of conception:Summer
Baby's zodiac sign:Pisces
Chinese zodiac:Goat
How it works
A conception calculator estimates when conception likely occurred and the fertile window, working back from your last period and cycle length. Ovulation typically happens about 14 days before the next period, and conception occurs around then.
Conception timing
Ovulation ≈ LMP + (cycle length − 14 days) Conception ≈ due date − 266 days
- LMP
- first day of last menstrual period
- cycle length
- days between periods (often ~28)
Worked example
- LMP = March 1
- 28-day cycle
- Ovulation ≈ March 1 + (28 − 14) = March 15
Likely conception around March 15, give or take a few days.
Good to know
- Sperm can survive ~5 days, so the fertile window spans several days before ovulation.
- Cycle length varies, so this is an estimate — ovulation tests pinpoint it better.
- Conception date differs from gestational age, which is measured from the LMP.