Pregnancy Due Date

Naegele's Rule for Due Date Calculation

Adds 280 days (40 weeks) to the first day of your last menstrual period (LMP), assuming a standard 28-day cycle.

Pregnancy Trimester Milestones

First Trimester: Weeks 1|13. Second Trimester: Weeks 14|27. Third Trimester: Weeks 28|40.

Conception Date vs. LMP Date

If your exact conception date or ovulation date is known (e.g. through IVF or ovulation tracking), add 266 days for the estimated due date.

Related Calculators