Due Date Calculator
Estimate your baby’s expected date of birth
❓ How the calculator works
The calculator estimates the due date (EDD) from the first day of your last period and cycle length. It also shows the current pregnancy week, days remaining, and trimester.
The calculation uses Naegele’s rule adjusted for menstrual cycle length.
📐 Formula
EDD = LMP + 280 days + (Cycle − 28)
- LMP — first day of the last menstrual period
- Cycle — average cycle length in days (usually 28)
- Week = (Today − LMP) / 7 + 1
👶 Trimesters
- 1st trimester — weeks 1–13
- 2nd trimester — weeks 14–26
- 3rd trimester — weeks 27–40+
✅ Tips
- Only about 5% of babies are born on the exact due date — treat it as a guide, not a guarantee.
- A doctor can refine dates with a first-trimester ultrasound.
- Always follow your obstetrician’s guidance for prenatal care.