Compare · Pregnancy Conception Calculator
Two independent scenarios side by side.
Scenario A
Due date
Estimated conception
2/25/2026
Due date − 266 days
Likely window (±5 days)
2/20/2026 – 3/2/2026
Most likely day-of-conception range
First day of last period
2/11/2026
LMP ≈ due − 280 days (Naegele)
Scenario B
Due date
Estimated conception
2/25/2026
Due date − 266 days
Likely window (±5 days)
2/20/2026 – 3/2/2026
Most likely day-of-conception range
First day of last period
2/11/2026
LMP ≈ due − 280 days (Naegele)