Due Date Calculator

Pregnancy Due Date Estimator — fast, accurate, and easy to use.

Estimate using:

Last Menstrual Period • Conception Date • Gestational Age


How to calculate

Choose the most accurate starting point available (LMP is common). The calculator uses Naegele’s rule (LMP + 280 days) by default.








Definition

A pregnancy due date estimates when a baby is likely to be born. Clinically, due date is commonly calculated as 280 days (40 weeks) from the first day of the last menstrual period (LMP).

Real-world use cases

  • Expecting parents planning maternity/paternity leave and appointments.
  • Clinics providing quick estimates during early visits.
  • Midwives and doulas scheduling prenatal classes and check-ins.

Benefits

  • Fast, privacy-friendly calculation (client-side).
  • Multiple input methods for better accuracy.
  • Clear outputs suitable for sharing with providers.

Disclaimer:

This calculator provides an estimate only and does not replace clinical assessment. For medical advice, diagnosis, or personalized care, consult a healthcare professional. Ultrasound dating may change the estimated due date.
Frequently Asked Questions (FAQ)
  1. Q: Which date is most accurate — LMP or conception?
    A: LMP is commonly used; conception date can be more accurate if known (e.g., IVF). First-trimester ultrasound is the clinical gold-standard for dating.
  2. Q: Can a due date change?
    A: Yes — early ultrasound measurements often adjust the estimated due date.
  3. Q: Does the calculator predict exact day of birth?
    A: No — it estimates a due date; most births occur within a range around that date.
  4. Q: Is this tool private?
    A: Yes — calculations happen client-side in your browser; no data is sent to servers by this tool itself.
  5. Q: What if I have irregular cycles?
    A: Irregular cycles can affect accuracy; consult your provider for personalized dating (ultrasound recommended).
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