Pregnancy Due Date Calculator
Calculate your baby's due date and gestational age
Calculate your due date using LMP, conception date, or adjust for irregular cycles
Your Pregnancy Timeline
Pregnancy Milestones
Evidence-Based Information
Based on scientific research and guidelines from leading health organizations
Understanding Pregnancy Calculations
How Due Dates Are Calculated
- • Based on 40 weeks from first day of last menstrual period
- • Assumes 28-day cycle with ovulation on day 14
- • Only about 5% of babies are born on their exact due date
- • Most births occur between 37 and 42 weeks
Important Notes
- • This calculator provides an estimate only
- • Always consult with your healthcare provider
- • Ultrasound dating is more accurate
- • Many factors can affect actual delivery date
Pregnancy Due Date Calculator: Calculate Your Baby's EDD & Gestational Age
Calculate your pregnancy due date accurately! Use our advanced pregnancy calculator with LMP, conception date, or IVF transfer. Get your baby's EDD, gestational age, and week-by-week pregnancy timeline instantly.
Your Pregnancy Journey Starts Here: When Is Your Due Date?
Congratulations on your pregnancy! One of the first and most exciting questions you have is: "When will my baby arrive?"
Knowing your Estimated Due Date (EDD) is the key to your entire pregnancy journey. It helps you and your doctor schedule checkups, monitor your baby's development, and prepare for the big day.
Our comprehensive due date calculator is more than just a simple tool. It supports multiple calculation methods—from your last period to your IVF transfer date—to give you the most accurate estimate possible.
Ready to see your timeline? Find your estimated due date in seconds.
Calculate Your Due Date Now🧮 How to Calculate Your Pregnancy Due Date: 4 Key Methods
While every pregnancy is unique, doctors use several trusted methods to estimate your due date. Our calculator can use all of them.
| Calculation Method | What It Is | Best For... | Key Consideration |
|---|---|---|---|
| LMP | 40 weeks (280 days) from your last period | Women with regular 28-day cycles | Assumes you ovulated on Day 14. Less accurate for irregular cycles |
| Conception Date | 38 weeks (266 days) from your conception date | Women who know their exact ovulation date | Requires diligent tracking (kits, BBT, etc.) |
| Ultrasound | Measures the fetus's size (CRL) to find gestational age | Everyone. Especially vital in the first trimester | Considered the most accurate method for confirming or adjusting the EDD |
| IVF Transfer | Uses the exact date of embryo transfer | Women who have undergone IVF | The most precise, scientifically-based calculation |
1. Last Menstrual Period (LMP) - The Standard Pregnancy Calculation
This is the most common way to calculate an EDD. It's based on the first day of your last menstrual period (LMP).
How it works: A full-term pregnancy lasts about 40 weeks (280 days). This method calculates your EDD by adding 280 days to your LMP.
The Formula (Naegele's Rule):
(First Day of LMP + 7 Days) - 3 Months + 1 Year = EDD
Best for: Women with regular 28-day menstrual cycles.
2. Conception Date - The Precise Method
If you were tracking ovulation and know your exact conception date, this method is highly accurate.
How it works: This method adds 266 days (38 weeks) to your known conception date.
Why 38 weeks? The 40-week "LMP" method includes the ~2 weeks before you actually ovulated and conceived. This method starts from conception, so it's 38 weeks.
Best for: Women who used ovulation test kits, tracked basal body temperature, or know the exact date of intercourse.
🗓️ Your Pregnancy Timeline: What to Expect After You Get Your EDD
Your due date is the anchor for your 40-week pregnancy calendar. Here's a quick guide to the milestones in each trimester.
First Trimester
Weeks 1–13
Second Trimester
Weeks 14–27
Third Trimester
Weeks 28–40+
Medical Accuracy & Clinical Validation
Our pregnancy due date calculator uses the same medical formulas and algorithms that healthcare providers use in clinical practice. The calculations are based on:
- Naegele's Rule - The standard medical formula for due date calculation
- ACOG Guidelines - American College of Obstetricians and Gynecologists standards
- CRL Measurements - Crown-rump length data for ultrasound dating
- IVF Protocols - Embryo transfer dating standards
Frequently Asked Questions (FAQ)
How accurate is the due date calculator?
It is an estimate. Only 5% of babies are born on the exact date. Most arrive within a week before or after.
Can I use this with irregular periods?
Yes, but the result may be less accurate. An early ultrasound is the best dating method for irregular cycles.
How is it calculated?
Standard calculation adds 280 days (40 weeks) to the first day of your last menstrual period (LMP).
Common Pregnancy Calculator Questions
- • How to calculate pregnancy weeks from last period?
- • What is my due date based on ovulation?
- • Pregnancy calculator for irregular periods
- • How many weeks pregnant am I exactly?
- • When did I conceive based on due date?
- • Baby due date calculator with cycle length
- • Pregnancy timeline week by week
- • EDD calculator for IVF pregnancies
- • Gestational age calculator from ultrasound
- • How to calculate due date from conception?
Trusted by Expecting Parents Worldwide
Our pregnancy calculator serves expecting families across the United States, United Kingdom, Canada, Australia, and globally. Whether you're in New York, London, Toronto, or Sydney - get accurate due date calculations tailored to your location and healthcare system.
Your Journey Awaits
Your Estimated Due Date is the first big milestone in an incredible journey. Use this date to partner with your doctor, plan for the future, and get excited for all the changes to come.
Ready to start planning?
Calculate My Due Date and See My Timeline!Medical Disclaimer
This Pregnancy Due Date Calculator is an educational tool designed to provide general information and should not be considered medical advice. The results are based on standard guidelines and may not account for individual health circumstances, genetic factors, or concurrent medical conditions. Always consult with a qualified healthcare professional for proper interpretation of your results, personalized target goals, and treatment recommendations. Do not make changes to medications or treatment plans without consulting your physician.
Sources and References
The information and calculations on this page are based on established guidelines and research from leading health organizations. We are committed to providing accurate and transparent information.
- American College of Obstetricians and Gynecologists - "Methods for Estimating the Due Date"
- World Health Organization - "Ultrasound for Gestational Age Assessment"
- National Institutes of Health - "Pregnancy Dating Guidelines"
- Royal College of Obstetricians and Gynaecologists - "Ultrasound Screening Guidelines"
Frequently Asked Questions (FAQ)
How accurate is the pregnancy due date calculator?
Our calculator provides estimates based on standard medical formulas (Naegele's Rule) and is highly accurate for women with regular 28-day cycles. However, only about 5% of babies are born exactly on their due date. Most births occur within a week before or after the estimated date. For the most accurate dating, always follow up with ultrasound confirmation from your healthcare provider.
Can I use this calculator if I have irregular periods?
Yes, our calculator includes options for custom cycle lengths, which can help adjust for irregular periods. However, the LMP method becomes less reliable with irregular cycles. If your cycles are consistently irregular, an early ultrasound dating scan will provide the most accurate due date estimate.
What's the difference between gestational age and fetal age?
Gestational age is calculated from the first day of your last menstrual period (LMP), while fetal age (also called embryonic age) is calculated from the actual date of conception. Gestational age is typically about two weeks longer than fetal age. Healthcare providers use gestational age as the standard for pregnancy dating.
How does ultrasound dating work for pregnancy?
Ultrasound dating measures the baby's size, particularly the crown-rump length (CRL) in the first trimester, to estimate gestational age. First-trimester ultrasounds (before 14 weeks) are the most accurate for dating, with an accuracy of ±5-7 days. Later ultrasounds become less accurate for dating purposes.
What if my doctor's due date differs from the calculator's result?
It's common for healthcare providers to adjust due dates based on ultrasound measurements, especially if there's a significant discrepancy from the LMP calculation or if you have irregular cycles. Always follow your healthcare provider's official due date, as they have access to your complete medical history and diagnostic tools.