Pregnancy Due Date Calculator
Estimate the last menstrual period, estimated due date, current gestational age and time remaining in pregnancy.
How to Use This Calculator
- Select LMP, EDD or current gestational age.
- Enter the relevant date or gestational age.
- Select Calculate.
- Confirm the estimate clinically when required.
Choose the calculation method: LMP, EDD or gestational age.
Assumes 28-day cycle
Estimated Due Date
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Current Gestational Age
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Frequently Asked Questions
What does this pregnancy calculator estimate?
It estimates the last menstrual period, estimated due date and current gestational age based on the selected calculation method.
How is the estimated due date calculated from LMP?
The calculator adds 280 days, or 40 weeks, to the first day of the last menstrual period.
Can I calculate the last menstrual period from an estimated due date?
Yes. The calculator subtracts 280 days from the estimated due date to estimate the last menstrual period.
Does this calculator account for irregular menstrual cycles?
No. It assumes a 28-day menstrual cycle, so the result may be less accurate for irregular or longer or shorter cycles.
Can this calculator replace ultrasound dating?
No. The result is an estimate and should be confirmed with clinical assessment and ultrasound dating when indicated.
References
- American College of Obstetricians and Gynecologists. Methods for estimating the due date.
- World Health Organization. Recommendations on antenatal care for a positive pregnancy experience.
- Standard Naegele rule calculation using 280 days from the first day of the last menstrual period.