EDD Calculator

Author: Henrick Yau
- 13 October 2026
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Calculators

Estimated Due Date (EDD) Calculator

Calculate your estimated due date and track pregnancy milestones based on your last menstrual period (LMP) or conception date. This calculator provides comprehensive pregnancy timeline information for expectant parents and healthcare providers.

Calculation Method

Typical range: 21-35 days
First day of your last period

Current Information

Automatically set to today

Advanced Options

Understanding Pregnancy Dating

Accurate pregnancy dating is essential for proper prenatal care. Different methods are used depending on available information, with each having specific applications and accuracy levels.

Dating Methods
  • Last Menstrual Period (LMP): Most common method, assumes 28-day cycle with ovulation on day 14
  • Conception Date: When fertilization occurred, typically 14 days after LMP in regular cycles
  • Ultrasound Dating: Most accurate in first trimester, measures fetal development
  • IVF Dating: Most precise method since exact conception timing is known
Pregnancy Timeline
  • Gestational Age: Calculated from LMP (40 weeks total)
  • Fetal Age: Calculated from conception (38 weeks total)
  • First Trimester: Weeks 1-12 (organ development)
  • Second Trimester: Weeks 13-27 (rapid growth)
  • Third Trimester: Weeks 28-40 (maturation and preparation for birth)
Important Notes
  • Only 5% of babies are born exactly on their due date
  • Term pregnancy is considered 37-42 weeks
  • First trimester ultrasound is most accurate for dating (ยฑ5-7 days)
  • Later ultrasounds become less accurate for dating
  • Individual variations in cycle length affect LMP calculations
Naegele's Rule
  • Traditional calculation: LMP + 280 days (40 weeks)
  • Alternative: LMP + 1 year - 3 months + 7 days
  • Assumes 28-day cycle with ovulation on day 14
  • Adjustments needed for different cycle lengths

Disclaimer: This calculator provides estimates for educational purposes only and should not replace professional medical advice. Actual due dates may vary based on individual factors. Always consult with your healthcare provider for accurate pregnancy dating and prenatal care recommendations.

What Is the Estimated Due Date (EDD) Calculator?

The Estimated Due Date (EDD) Calculator is a straightforward, useful tool designed to predict the expected delivery date of a baby. By entering key details such as the last menstrual period (LMP), conception date, ultrasound scan data, or IVF transfer date, the calculator provides a clear timeline of pregnancy progress. It is ideal for expectant parents, midwives, and healthcare professionals who want to estimate the baby's arrival, monitor developmental milestones, and stay on track with antenatal appointments.

How the Due Date Is Calculated

The most common method for calculating the EDD is based on Naegeleโ€™s Rule, which assumes a regular 28-day menstrual cycle.

Formula (Naegeleโ€™s Rule):
Estimated Due Date = First Day of Last Menstrual Period + 1 Year โˆ’ 3 Months + 7 Days

If your cycle length differs from 28 days, the calculator adjusts the result based on your input. IVF and ultrasound-based dating are also supported for more precise predictions.

Plan your pregnancy timeline and due date

The EDD Calculator helps you:

  • Calculate due date based on different methods
  • Track pregnancy timeline including trimesters and weekly development
  • Estimate conception date and fetal age
  • Visualise milestones such as viability, full term, and expected delivery
  • Plan antenatal care with recommended check-ups and tests

Calculate your due date in a few steps

Follow these simple steps to get your estimated due date and pregnancy timeline:

  • Select your calculation method (LMP, conception date, ultrasound, or IVF)
  • Enter the relevant date based on your chosen method
  • Adjust your cycle length if different from 28 days
  • Set todayโ€™s date (auto-filled) and choose your time zone if needed
  • Optionally enable details like trimester breakdown, weekly development, appointments, and milestones
  • Click โ€œCalculate Due Dateโ€ to view your personalised pregnancy chart

Multiple methods, trimester views and milestone tracking

  • Multiple calculation methods including LMP, conception, ultrasound, and IVF
  • Trimester visualisation with start and end dates
  • Weekly baby development insights based on gestational age
  • Pregnancy milestone tracking for important events
  • Appointment scheduler with week-by-week visit recommendations

How This Tool Supports Your Journey

Whether you are looking to estimate your due date, track your pregnancy week-by-week, or plan your antenatal care, this tool offers a reliable and easy-to-use experience. It complements other tools such as:

Questions about due date accuracy and calculation methods

What is the most accurate method to calculate due date?

First-trimester ultrasounds and IVF dates are usually the most precise methods because they are based on observable measurements or known fertilisation times.

Can I use this if I donโ€™t know my exact LMP?

Yes. If you are unsure of your LMP, you can use the conception date, ultrasound scan details, or IVF transfer date for a more accurate estimate.

What if I have irregular cycles?

The calculator lets you adjust your average cycle length, which helps improve accuracy. For irregular cycles, an early ultrasound is recommended.

Can this predict my baby's gender?

No, this tool does not predict gender. However, the timeline will show when gender may be visible on an ultrasound, typically around 16 weeks.

Is this tool a substitute for medical advice?

No. The calculator provides educational estimates. Always consult a healthcare provider for personalised medical guidance and diagnosis.

A practical tool for pregnancy planning and monitoring

The Estimated Due Date Calculator is a practical and informative way to plan and monitor your pregnancy. From estimating your babyโ€™s arrival to understanding key milestones and appointments, this tool supports a well-informed and prepared experience throughout pregnancy.