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Pregnancy Due Date Calculator (EDD)

Estimate your due date from LMP, see your current week/trimester, and view a week-by-week timeline

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Calculator

Estimate due date, milestones, and progress

Calculate based on

Uses Naegele’s rule (adds 280 days). Early ultrasound may refine dates.

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How it works

This calculator estimates your estimated due date (EDD) from the first day of your last menstrual period (LMP). Pregnancy dating is traditionally measured from LMP because it’s often the most reliable reference point.

After calculating the EDD, the calculator can also estimate: current gestational age (weeks + days), trimester, and a week-by-week timeline with key milestones.

Timeline fun-factor: Your week-by-week bar can optionally show “baby is about the size of…” using a Fruit or Animal view (toggle at the top of the timeline).

Dating is an estimate—confirm with your antenatal provider and follow local clinical guidelines.

Formula

Estimated Due Date (EDD) = LMP + 280 days (40 weeks)
Gestational age (days) = Today − LMP
Gestational age (weeks) = floor((Today − LMP) ÷ 7)

Frequently asked questions

Clinical reminder: Always follow local protocols and consult medication information sheets. These examples are for calculation practice only.

References & sources

For pregnancy dating, screening windows, and safety guidance, use trusted maternity references and follow your local service policy.

American College of Obstetricians and Gynecologists (ACOG)

Guidance on estimating due date and prenatal care.

World Health Organization (WHO)

Pregnancy and maternal health guidance and resources.

Healthdirect Australia – Pregnancy week by week

Australian consumer-friendly pregnancy timelines and milestones.

RANZCOG (Australia & New Zealand)

Professional guidance for obstetrics and maternity care.

Medical disclaimer: This calculator provides an estimate only and does not replace clinical assessment, ultrasound dating, or local maternity guidelines.

Related Calculators

Gestational Age Calculator
Conception Date Calculator
Ovulation Calculator
BMI Calculator
Unit Conversions

Evidence-based safety

Dating can be revised by ultrasound and clinical context. Use this calculator for planning and education—confirm important decisions with your antenatal provider.

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  • Not stored by us
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