Due Date Calculator
Estimate your baby's due date
Formula
LMP method: LMP + 280 days
Conception method: Date + 266 days
Based on Naegele's rule. Adjusted for cycle length variations.
Trimester Timeline
1st Trimester
Weeks 1–12
Major organs form. Morning sickness common.
2nd Trimester
Weeks 13–26
Baby grows rapidly. Movement felt. Energy returns.
3rd Trimester
Weeks 27–40
Baby gains weight and prepares for birth.
FAQ
What if I don't know my last period date?
Use the conception date mode if you know approximately when conception occurred. An ultrasound in early pregnancy can also provide an accurate due date.
Can I change my cycle length?
Yes — if your average cycle is longer than 28 days, ovulation happens later, shifting your due date forward. The calculator adjusts for cycles from 20 to 45 days.