How accurate is the LMP due date?

The LMP due date assumes a 28-day cycle with ovulation on day 14. It is accurate to within about ±2 weeks. Ultrasound dating in the first trimester is more accurate, especially for irregular cycles.

What does full term mean?

Full term is 39-40 weeks of gestation. Early term is 37-38 weeks. Late term is 41 weeks. Post-term is 42+ weeks. Babies born before 37 weeks are preterm.

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Pregnancy Due Date Calculator

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First Day of Last Menstrual Period

Enter your date to calculate the due date

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Calculate due date using LMP (Naegele's rule), conception date, IVF transfer, or ultrasound. Shows gestational age, trimester, weeks remaining, and key milestones.

How to Use

1Select your input method: LMP, Conception Date, IVF Transfer, or Ultrasound
2Enter the relevant date (and gestational age if using ultrasound)
3Click Calculate to see your estimated due date, current gestational age, and trimester
4The milestone timeline shows key dates throughout pregnancy
5Always consult your OB/GYN for medical advice - this is an estimate only

Features

4 input methods: LMP, Conception Date, IVF Transfer, Ultrasound
Estimated due date with gestational age and trimester
Weeks remaining calculation
Key milestone timeline (heartbeat, anatomy scan, full term)
Medical disclaimer included
100% browser-based

Pregnancy Due Date Calculator

How to Use

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