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
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.
Medical disclaimer
Please read before using this calculator. Your safety and appropriate prenatal care always come first.
Informational use only
This pregnancy calculator is for general informational and educational purposes only. It does not provide medical advice, diagnosis, or prenatal care. It is not a substitute for care from a qualified midwife, obstetrician, or other licensed healthcare professional.
Using this tool does not create a doctor–patient relationship with DoctorBookly or any provider listed on the platform. It cannot confirm pregnancy, assess fetal health, or replace laboratory or ultrasound evaluation.
About due date estimates
Estimated due dates vary individually. Only about 4–5% of babies are born on the exact calculated date. Ultrasound dating, clinical assessment, and your provider's judgment may differ from this estimate — always follow your prenatal care team's guidance.
- Results depend on the accuracy of the dates you enter (LMP, conception, or IVF transfer).
- Irregular cycles, ovulation timing, assisted reproduction, and multiple gestations can affect dating.
- First-trimester ultrasound (crown–rump length) is often more reliable than LMP-based estimates alone.
- International guidelines may differ; your local clinician's dating should take precedence.
DoctorBookly's role
DoctorBookly connects users with healthcare resources and educational tools. We do not deliver clinical obstetric services, interpret scan results, prescribe treatment, or monitor pregnancies through this tool.
For personalised advice, scheduling, and ongoing prenatal care, consult a qualified healthcare professional in your country or region.