Enter the first day of your last menstrual period and your average cycle length, and the calculator instantly estimates your baby’s due date using Naegele’s rule. It also shows your conception date, fertile window, and the end dates of your first and second trimesters.
Free due date calculator – no sign‑up
Calculate Your Due Date in Seconds
Find out when your baby is expected to arrive using your last period, conception date, or IVF transfer date. Get your personalized estimated due date, current week, trimester, and a countdown — all free, private, and instant.
Count Down to Your Baby’s Arrival with Precision
One of the most exciting moments in pregnancy is learning your estimated due date. Our Due Date Calculator gives you that date in seconds, using the most reliable method for your situation. Whether you know the first day of your last period, your conception date, or your IVF transfer date, the tool instantly provides your baby’s expected birthday, your current pregnancy week, and a visual countdown. It’s completely free, private, and designed to be your trusted companion from the first trimester to delivery day.
What Is a Due Date Calculator?
A due date calculator is a free online tool that estimates the expected date of delivery (EDD) for a pregnancy. You can calculate your due date using several common starting points: the first day of your last menstrual period (LMP) with Naegele’s Rule, the exact conception date (if known), or the date of an embryo transfer during IVF. The calculator adjusts for your individual cycle length or embryo age to provide the most accurate estimate. It also shows your current gestational week, how many days remain, and a progress timeline. While only about 4% of babies arrive exactly on their due date, it remains the essential reference point for prenatal care, maternity planning, and baby preparations.
How to Use the Due Date Calculator
Choose Your Starting Point
Select the method you have: first day of your last period, the date of conception, or an IVF transfer date. The calculator adapts to each scenario.
Enter the Required Details
For LMP, provide the date and your typical cycle length. For conception or IVF, provide the exact date and (for IVF) the embryo age at transfer.
View Your Due Date & Timeline
Instantly see your estimated due date, current week of pregnancy, trimester, and a visual countdown — no sign‑up required.
How the Due Date Calculator Determines Your Date
The calculator uses three different formulas depending on your input. For LMP, it applies Naegele’s Rule: Due Date = LMP + 280 days + (Cycle Length – 28). For a known conception date, it adds 266 days to estimate the due date. For IVF, it uses Due Date = Transfer Date – Embryo Age + 266 days (e.g., for a Day 5 blastocyst, subtract 5 days). Gestational age is calculated from LMP (or adjusted LMP) to today. All computations run locally in your browser, so your personal dates remain completely private.
Key Formulas
LMP: Due = LMP + 280 + (Cycle – 28)
Conception: Due = Conception + 266 days
IVF: Due = Transfer – Embryo Age + 266
All results are adjusted to 40 weeks gestational age. Trimester classification is automatic.
Key Features of This Due Date Calculator
Multiple Input Methods
Works with LMP, conception date, or IVF transfer — no matter how your pregnancy started.
Personalized Cycle Adjustment
Customize the calculation for your actual cycle length, not just the 28‑day default.
Pregnancy Progress Tracker
Instantly see your current week, remaining days, and trimester — everything you need at a glance.
Private & Secure
Your dates and cycle details remain on your device. Nothing is ever uploaded or shared.
Benefits of an Accurate Due Date
- ✅ Plan prenatal visits – schedule important scans and check‑ups on time
- ✅ Prepare for maternity leave – provide your employer with a reliable expected date
- ✅ Monitor baby’s growth – know which developmental milestones are happening week by week
- ✅ Peace of mind – replace uncertainty with a medically recognized estimate
- ✅ Share the joy – announce your due date to loved ones with confidence
Due Date by LMP, Conception, or IVF
Last Menstrual Period (LMP)
The most common method. Enter the first day of your last period and your cycle length. The calculator applies Naegele’s Rule with a personalized adjustment.
Conception Date
If you know the exact date of conception (e.g., from ovulation tracking), the calculator adds 266 days to find your due date.
IVF Transfer Date
For IVF pregnancies, enter the embryo transfer date and the embryo’s age (e.g., 3‑day or 5‑day). The tool calculates an adjusted due date, often the most accurate of all.
Understanding Naegele’s Rule
Developed in the 19th century, Naegele’s Rule estimates the due date by adding 280 days (40 weeks) to the first day of the last menstrual period. The rule assumes a 28‑day cycle and ovulation on day 14. If your cycle is longer or shorter, the calculator adjusts the date accordingly (e.g., a 30‑day cycle adds 282 days). While simple, it’s still the starting point for most prenatal dating.
Early Ultrasound and Your Official Due Date
Most Accurate Method
An early pregnancy ultrasound (before 12 weeks) measures the baby from crown to rump and is the most accurate way to confirm or adjust the due date.
Using the Calculator Together
Run this calculator to get your initial estimate, then compare it with your scan result. If they differ by more than a week, your doctor may use the ultrasound date.
What If My Baby Arrives Before or After the Due Date?
It’s completely normal. Only about 4% of women deliver on their exact due date. Most first‑time mothers go into labor within a week after their due date. Full‑term is considered between 37 and 42 weeks. Your due date is a target, not an expiration date — use it to prepare, but stay flexible.
Example Due Date Calculations
Using LMP: If your last period started on June 1, 2025 and you have a 28‑day cycle, the due date is June 1 + 280 days = March 8, 2026. Using conception: If conception occurred on June 14, 2025, the due date is June 14 + 266 days = March 7, 2026. Using IVF: If a 5‑day blastocyst was transferred on June 20, 2025, the due date is June 20 – 5 + 266 = March 8, 2026. The calculator does all these variations instantly.
How to Use Your Due Date to Plan Ahead
Once you have your date, mark it on your calendar and use it to schedule prenatal classes, order nursery furniture, and plan maternity leave. Share it with your healthcare provider, partner, and close family. Many parents also use the due date to create a pregnancy countdown or to choose a baby shower date. This calculator gives you the starting number for all those exciting plans.
Factors That Affect Due Date Accuracy
- 📅 Cycle regularity and length
- 📏 Ultrasound measurements
- 🧬 Genetics and family history
- 🤰 Number of fetuses
- 📈 Maternal age and health
- 💊 Fertility treatments
- 🩺 Medical conditions
- 📋 LMP recall accuracy
Detailed IVF Due Date Scenario
Scenario: Day 5 blastocyst transferred on March 10, 2025.
- ✅ Adjusted transfer date (embryo age subtracted): March 10 – 5 = March 5
- ✅ Due date: March 5 + 266 days = November 26, 2025
- ✅ Current gestational age (if today is July 1, 2025): 16 weeks 5 days
- ✅ Days until due date: 148 days
- ✅ The calculator shows all these milestones at a glance.
Who Can Use This Due Date Calculator?
- 🤰 Expectant mothers – get an instant due date from your LMP, conception, or IVF transfer
- 👩⚕️ OB‑GYNs & midwives – quickly verify dates with multiple calculation methods
- 📋 Fertility specialists – provide patients with precise IVF due dates
- 👪 Partners & family – follow along with the pregnancy timeline
- 🎓 Childbirth educators – demonstrate how due dates are determined
Key Due Date Terms
- Estimated Due Date (EDD)
- The projected date of delivery, typically 40 weeks from the start of the last menstrual period.
- Naegele’s Rule
- The standard formula for calculating a due date from LMP: LMP + 280 days, adjusted for cycle length.
- Gestational Age
- The age of the pregnancy measured from LMP, expressed in weeks and days.
- Embryo Transfer Date
- In IVF, the day the fertilized embryo is placed into the uterus; used to calculate an accurate due date.
Tips for Using Your Due Date Wisely
- Schedule your first prenatal appointment soon after a positive pregnancy test.
- Start prenatal vitamins with folic acid right away if you haven’t already.
- Use the due date to plan your maternity leave, but give yourself a buffer — babies don’t always follow the calendar.
- Re‑run the calculator if an ultrasound adjusts your gestational age.
- Remember that only about 4% of babies are born on their due date; treat it as a guide, not a guarantee.
Advantages of This Due Date Calculator
- ✅ 100% free – no sign‑up, no ads
- ✅ Supports LMP, conception, and IVF transfer methods
- ✅ Instantly shows current week, trimester, and countdown
- ✅ Personalizes for your cycle length and embryo age
- ✅ Works on any device
- ✅ Private – your dates never leave your device
Limitations of Due Date Estimates
This calculator provides an estimate based on standard obstetric formulas. Individual factors such as irregular cycles, late ovulation, or early pregnancy bleeding can affect accuracy. An early ultrasound is the most reliable method for dating a pregnancy. Always consult your healthcare provider for your official due date.
Accuracy of Results
The formulas used are standard in obstetrics and provide the same result your doctor would calculate from your LMP or conception date. For IVF, the adjusted calculation is highly accurate, often within a day or two. However, natural biological variation means the actual delivery date can differ by a week or more.
Security and Privacy
All calculations are performed locally in your browser. No personal dates or cycle information is ever transmitted, stored, or shared. You can use the tool offline after the page loads.
Mobile‑Friendly Design
The due date calculator is fully responsive. Use it on your smartphone, tablet, or desktop — all inputs, charts, and results adapt seamlessly to any screen size.
Frequently Asked Questions
How do I calculate my due date?
The most common method is Naegele’s Rule: add 280 days (40 weeks) to the first day of your last menstrual period, then adjust for your cycle length. If you know the conception date, add 266 days instead. The calculator does all variations automatically.
Can I use this calculator if I’m having twins?
Yes, the due date is calculated the same way for singleton and twin pregnancies, though twins often arrive earlier. Your doctor will provide a more tailored timeline based on your specific situation.
Is the due date from LMP the same as from conception?
They should be very close — within a day or two. LMP‑based dating adds 280 days (assuming ovulation on day 14), while conception‑based dating adds 266 days. For a 28‑day cycle, they match exactly.
Why does the calculator ask for my cycle length?
Because women with longer cycles tend to ovulate later, which delays conception. The calculator adjusts the due date to account for this, giving you a more accurate estimate.
How do I calculate my IVF due date?
Enter the embryo transfer date and the age of the embryo (e.g., 3‑day or 5‑day). The calculator subtracts the embryo age and adds 266 days to provide the due date.
Is my personal data safe?
Absolutely. All calculations are local. No information is ever sent to a server or stored.
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Conclusion: Your Countdown to Baby’s First Hello
The due date is more than a number — it’s the milestone that organizes your pregnancy and builds anticipation for the biggest day of your life. This calculator gives you that date in seconds, no matter how you began your journey. Enter your details now and start counting down to the moment your family grows.
Ready to Find Your Due Date?
Enter your LMP, conception date, or IVF transfer now – free, private, and instant.