Due Date Estimator

Author: Henrick Yau
- 1 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 (±5-7 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 and useful tool designed to estimate when your baby might arrive. By entering key details such as your last menstrual period (LMP), conception date, ultrasound scan results, or IVF transfer date, the calculator generates a clear overview of your pregnancy timeline. It is particularly helpful for expectant parents, midwives, and healthcare professionals who wish to anticipate the baby's arrival, track developmental milestones, and keep up with antenatal appointments.

How the Due Date Is Calculated

The most widely used method for estimating the EDD is Naegele’s Rule, which assumes a regular 28-day menstrual cycle.

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

If your cycle is not 28 days, the calculator modifies the result based on the information you provide. It also supports IVF and ultrasound-based dating for greater precision.

Track pregnancy milestones and due dates

The EDD Calculator helps you:

  • Calculate due date using various methods
  • Monitor pregnancy timeline including trimesters and weekly changes
  • Estimate conception date and fetal age
  • Visualise milestones such as viability, full term, and expected delivery
  • Plan prenatal care with suggested check-ups and screenings

Calculate due date with LMP, conception, or IVF

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

  • Choose your calculation method (LMP, conception date, ultrasound, or IVF)
  • Enter the relevant date for the method you selected
  • Adjust your cycle length if it differs from 28 days
  • Set today’s date (pre-filled) and select your time zone if necessary
  • Optionally enable details like trimester breakdown, weekly development, appointments, and milestones
  • Click “Calculate Due Date” to see your personalised pregnancy chart

Multiple methods 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 significant events
  • Appointment scheduler with week-by-week visit suggestions

How This Tool Supports Your Journey

Whether you're hoping to estimate your due date, track your pregnancy week-by-week, or organise your prenatal care, this tool offers a dependable and user-friendly experience. It works well alongside other resources such as:

Questions about due date accuracy and methods

What is the most accurate method to calculate due date?

First-trimester ultrasounds and IVF dates tend to be the most precise, as they rely on measurable data or known fertilisation times.

Can I use this if I don’t know my exact LMP?

Yes. If you're 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 allows you to adjust your average cycle length, which can improve accuracy. For irregular cycles, an early ultrasound is advisable.

Can this predict my baby's gender?

No, this tool does not predict gender. However, the timeline will indicate when gender might be visible on a scan, usually around 16 weeks.

Is this tool a substitute for medical advice?

No. The calculator offers educational estimates only. Always consult a healthcare provider for personalised medical advice and diagnosis.

Plan your pregnancy with due date insights

The Estimated Due Date Calculator is a practical and informative way to plan and manage your pregnancy. From estimating your baby’s arrival to understanding important milestones and appointments, this tool helps you stay informed and prepared throughout your pregnancy journey.