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Find your estimated due date in seconds.

Enter your last menstrual period, conception date or IVF transfer date and instantly see your EDD, gestational age in weeks, trimester and a visual pregnancy timeline.

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Due Date Calculator — EDD
LMP · Conception · IVF transfer (3-day or 5-day embryo)
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Your information

days
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Your result

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estimated due date
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Gestational age today weeks + days from LMP—
Trimester—
Conception date (est.)—
Days remaining—
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How it's calculated

Three methods, one result — your estimated due date

The Due Date Calculator uses three evidence-based methods to estimate your EDD. From the LMP, it applies Naegele's rule: add 280 days (40 weeks). From the conception date, it adds 266 days (38 weeks of fetal development). For IVF, embryo age at transfer is factored in — 3-day embryos add 3 days to the transfer date before applying the 266-day rule, giving transfer date + 263 days; 5-day blastocysts give transfer date + 261 days.

Naegele's rule (LMP method) assumes ovulation on day 14 of a 28-day cycle. If your cycle differs, the calculator adjusts the EDD by the difference from 28 days.

EDD (LMP) = LMP date + 280 days ± cycle offset
EDD (conception) = Conception + 266 days
EDD (IVF 3-day) = Transfer + 263 days
EDD (IVF 5-day) = Transfer + 261 days
  1. 1
    Identify reference date and method
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  2. 2
    Add the method-specific days to reach EDD
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  3. 3
    Calculate gestational age from LMP to today
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  4. 4
    Determine trimester and days remaining
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Understand the terms

EDD (Estimated Due Date)
The date that is 280 days after the first day of the LMP. Also called the expected date of confinement (EDC) or due date. About 5% of babies are born on this exact day.
Gestational age
The age of the pregnancy in weeks and days, counted from the first day of the LMP. At conception, gestational age is already ~2 weeks.
Trimester
One of three roughly equal periods of pregnancy. First: weeks 1–13. Second: weeks 14–26. Third: weeks 27–40.
Naegele's rule
A formula developed in the 19th century by Franz Naegele: EDD = LMP + 280 days. It assumes a 28-day cycle with ovulation on day 14.
LMP (Last Menstrual Period)
The first day of the last menstrual period before pregnancy. It is the standard reference point for gestational age and EDD calculation.
See the full glossary →
Disclaimer: estimation tool for informational and planning purposes. The EDD is a statistical midpoint — only about 5% of babies are born on their exact due date. Most births occur within two weeks before or after the EDD. This calculator does not replace clinical assessment or ultrasound dating by your healthcare provider.
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Frequently asked questions — Due Date

How is the estimated due date calculated?
The most common method is Naegele's rule: add 280 days (40 weeks) to the first day of your last menstrual period. From a known conception date, add 266 days (38 weeks of fetal development). For IVF, add 263 days for a 3-day embryo transfer or 261 days for a 5-day blastocyst transfer.
What is gestational age?
Gestational age is the number of weeks and days of pregnancy counted from the first day of the last menstrual period. At actual conception (usually day 14 of a 28-day cycle), the gestational age is already 2 weeks. A full-term pregnancy is 40 weeks of gestational age.
What are the three trimesters of pregnancy?
The first trimester spans weeks 1–13: the embryo implants and major organs begin forming. The second trimester covers weeks 14–26: the fetus grows rapidly and movements become noticeable. The third trimester runs from week 27 to birth: the baby gains weight and the lungs mature in preparation for delivery.
How accurate is the estimated due date?
Only about 5% of babies are born on their exact due date. The EDD is a statistical midpoint — most full-term births occur between 38 and 42 weeks. An early ultrasound (before 14 weeks) can provide a more accurate EDD than LMP alone, especially if your cycle is irregular.
What is the difference between a 3-day and a 5-day IVF transfer?
In IVF, embryos are cultured for either 3 days (cleavage stage) or 5 days (blastocyst). Because the embryo is already 3 or 5 days old at transfer, its age is added before applying the 266-day rule from conception. A 3-day transfer: EDD = transfer date + 263 days. A 5-day blastocyst transfer: EDD = transfer date + 261 days.

📚 Learn more — official sources

📋 Guideline ACOG — Methods for Estimating the Due Date (Committee Opinion 700) American College of Obstetricians and Gynecologists guidance on EDD estimation from LMP, ultrasound and ART, including IVF transfer dating. See official guideline → 🏛️ Organization WHO — WHO recommendations on antenatal care for a positive pregnancy experience World Health Organization comprehensive antenatal care guidelines covering gestational age assessment, trimester visits and birth preparation. See official source → 🏛️ Organization NHS — Antenatal appointments and due date UK National Health Service guide to pregnancy dating, including how ultrasound scans are used to confirm or adjust the estimated due date. See official source → 🔬 Study Naegele's rule revisited — accuracy of LMP-based dating (PubMed) Systematic review examining the accuracy of Naegele's rule and the role of first-trimester ultrasound in improving gestational age estimation. See on PubMed →

About the Due Date Calculator

The estimated due date (EDD) is the cornerstone of prenatal planning. This calculator implements the three methods recommended by ACOG and the WHO: Naegele's rule from the LMP (the standard clinical approach), dating from a known conception date, and dating from an IVF embryo transfer for pregnancies achieved through assisted reproductive technology.

The pregnancy timeline shows your current position across all three trimesters, giving you an at-a-glance view of how far along you are and how many days remain. Remember that the EDD is a statistical estimate — only about 5% of babies arrive on the exact date. Always confirm your due date with your healthcare provider, ideally with an early ultrasound scan.

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