Pregnancy Due Date Calculator
Estimate your estimated delivery date (EDD), gestational age, and trimester using internationally recognized obstetric dating — from last period, conception, or IVF transfer.
Estimated due date
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Key milestones
Pregnancy week guide
Scroll through gestational weeks (1–40). After you calculate your due date, your current week is highlighted automatically.
Educational overview only — your clinician’s dating and care plan take priority.
How due dates are calculated
LMP (Naegele's rule)
Add 280 days (40 weeks) to the first day of your last menstrual period. This is the standard used by WHO-aligned prenatal care and most international guidelines.
Conception dating
If you know your conception date, add 266 days (38 weeks) to estimate due date — equivalent to LMP dating with a 28-day cycle.
IVF pregnancies
Due date from embryo transfer: Day 5 blastocyst +261 days; Day 3 embryo +263 days. These offsets account for embryonic age at transfer.
Clinical accuracy
First-trimester ultrasound (crown–rump length) is often more accurate than LMP alone, especially with irregular cycles. Your obstetric provider's EDD takes precedence.
Frequently asked questions
How is my due date calculated from my last period?
Naegele's rule adds 280 days (40 weeks) to the first day of your last menstrual period (LMP), assuming a 28-day cycle unless adjusted.
Is ultrasound more accurate than a calculator?
Early first-trimester ultrasound dating is generally more accurate than LMP alone, especially with irregular cycles. Follow your clinician's dating from prenatal care.
How is IVF dating different?
Embryo transfer date is adjusted: Day-5 blastocyst transfer typically uses transfer date minus 19 days as equivalent LMP; Day-3 uses minus 17 days.