Pregnancy Due Date Calculator
Estimate your due date from the first day of your last period.
Not medical advice. This calculator gives a general estimate. It cannot diagnose or treat any condition. Please speak to a qualified doctor about your health.
The estimated due date (EDD) is calculated with Naegele’s rule: 280 days (40 weeks) from the first day of your last menstrual period (LMP), adjusted if your cycle is longer or shorter than 28 days.
Trimesters
- First trimester: up to week 13
- Second trimester: weeks 14 to 27
- Third trimester: week 28 until birth
Only a small share of babies arrive exactly on the due date. Full-term birth can be anywhere from week 37 to week 42. Your doctor may revise the date after an early ultrasound.
Last reviewed 7 November 2026. The formula and assumptions are shown above, and results are estimates, not advice.
Frequently asked questions
What if my cycles are irregular?
The LMP method is less accurate. Your doctor will usually date the pregnancy by ultrasound.
Can I get pregnant outside the typical window?
This calculator only estimates a due date from your LMP. See a doctor for fertility questions.