Pregnancy Due Date Calculator
Want to Know your Expected Due Date?
Use our simple pregnancy calculator to find out your estimated due date. Just enter the first day of your last period or your conception date. The tool will quickly give you a reliable due date, making it easier to follow your pregnancy journey.
How Is Your Estimated Due Date Calculated?
Estimating your due date is an essential step in your pregnancy journey. It helps you and your healthcare provider plan for prenatal care, track your baby’s growth, and prepare for delivery. There are several ways to calculate your due date, depending on the information you have. Every method for calculating a due date has a different level of accuracy, depending on the woman’s unique situation. Here are the most commonly used ways to estimate when your baby might arrive:
1. Last Menstrual Period (LMP)
That is the most commonly used approach. It calculates your due date by starting from the first day of your last period. This method is based on the assumption of a regular 28-day menstrual cycle, with ovulation typically happening around day 14. By adding 280 days (or 40 weeks) to the first day of your last period, your estimated due date is calculated. This method is easy and commonly used but may not be accurate for women with irregular menstrual cycles or those who ovulate earlier or later than day 14. If your cycle is longer or shorter than average, your due date may need to be adjusted.
2. Conception Date
If you know exactly when conception happened — for example, through ovulation tracking or fertility monitoring — this method provides a more accurate estimate. The due date is calculated by adding 266 days (or around 38 weeks) to the conception date. This method is helpful for women who monitor ovulation using ovulation predictor kits, basal body temperature, or fertility apps. It is also beneficial in cases where conception occurs through fertility treatments like IUI.
3. IVF (In Vitro Fertilization) Transfer Date
Women who conceive through IVF have the most precise information. The due date is calculated based on the exact date of the embryo transfer.
If a day-3 embryo was transferred, add 263 days to the transfer date.
If a day-5 embryo was transferred, add 261 days.
Because IVF involves precise medical tracking and exact dates, this method eliminates the uncertainties of natural conception and offers highly accurate results.
4. Ultrasound Scan
When the exact date of your last period or conception is unknown, an early ultrasound is one of the most reliable methods for estimating the due date. Ultrasounds taken during the first trimester (up to 12 weeks) can measure the fetus’s crown-rump length (CRL) to determine how far along the pregnancy is.
Ultrasounds are especially useful for women with irregular cycles, uncertain ovulation timing, or those who don’t recall their last menstrual period. In many cases, an ultrasound can provide a more accurate due date than calculations based on LMP.
How Accurate Is a Pregnancy Due Date?
Knowing your estimated due date helps you prepare for your baby’s arrival, but it’s essential to understand that it’s only an estimate. Many factors can affect the exact timing of your delivery.
Accuracy depends on things like your menstrual cycle, the method used to calculate the due date, and whether you’re using assisted methods like IVF. For example, the Last Menstrual Period (LMP) method assumes a 28-day cycle and ovulation on day 14 of the cycle. If your cycle is shorter, longer, or irregular, your estimated due date may not be exact. IVF and early ultrasounds tend to give more accurate results since they rely on exact dates or early fetal development.
While very few babies are born exactly on their due date, most arrive within two weeks before or after. That makes the due date a helpful guide, even if it isn’t exact.
Can My Due Date Change?
Yes, it can. A doctor may update your due date after an early ultrasound, especially if your baby’s size doesn’t match the original estimate or if your cycle length differs from the standard 28 days. New information obtained during pregnancy can also slightly affect the due date.
What If I Already Know My Due Date?
If you already have a due date, our Pregnancy Due Date Calculator is still helpful. By entering your due date, the tool gives you a complete pregnancy timeline—highlighting milestones, symptoms, upcoming prenatal tests, and reminders for doctor visits. It helps you stay on track and informed throughout your pregnancy.