Pregnancy Calculator

Your estimated due date is the approximate date your baby is expected to be born, typically 40 weeks from the first day of your last menstrual period. It's an estimate — only about 4% of babies are born exactly on their due date. Most births happen within two weeks before or after the EDD.

The most common method uses Naegele's Rule: add 280 days (40 weeks) to the first day of your last menstrual period, adjusted for your cycle length. Alternatively, your due date can be estimated from your conception date (add 266 days), an ultrasound measurement, or a known due date entered in reverse.

Due dates are estimates, not guarantees. Early ultrasounds (before 13 weeks) are generally the most accurate method. Calculations based on the last menstrual period assume a regular 28-day cycle, so if your cycle varies, your actual due date may differ. Your doctor may revise the date as your pregnancy progresses.

Yes. Your healthcare provider may adjust your due date based on ultrasound findings, especially in the first trimester. A significant difference between the ultrasound measurement and your LMP-based date can lead to a revised EDD. Later ultrasounds are less accurate for dating.

Select 'Due Date' as your calculation method and enter your known due date. The calculator will work backwards to estimate your conception date, last menstrual period, and current gestational age, and will display your pregnancy milestones going forward.

The World Health Organization defines a normal pregnancy as lasting between 37 and 42 weeks. A full-term birth is typically considered to occur between 39 and 40 weeks and 6 days. Births before 37 weeks are considered preterm, while those after 42 weeks are post-term.

Gestational age is measured in weeks and days from the first day of your last menstrual period. For example, if 10 weeks have passed since your LMP, you are 10 weeks pregnant. An ultrasound can confirm gestational age by measuring the baby's size.

While you cannot choose the exact day your baby arrives, knowing your estimated due date helps you plan prenatal care, maternity leave, and baby preparations. If you're considering fertility treatments or have a planned C-section, your medical team will work with you on timing.