A Pregnancy Due Date Calculator estimates the expected delivery date based on the first day of your last menstrual period (LMP), conception date, or ultrasound data. It helps you track your pregnancy timeline and plan ahead for prenatal care.

Most calculators use Naegele’s Rule, which adds 280 days (or 40 weeks) to the first day of your last menstrual period (LMP). This assumes a regular 28-day cycle. For irregular cycles, adjustments can be made based on ovulation or conception dates.

Yes. If you know your conception date (for example, after fertility tracking or IVF), simply add 266 days (or 38 weeks) to that date to estimate your due date.

If your cycle is longer than 28 days, your ovulation likely occurred later, so you can add extra days to the due date. For shorter cycles, subtract days accordingly. Many calculators allow you to input your average cycle length for better accuracy.

Due date calculators give an estimated date — only about 4–5% of babies are born exactly on that day. Most births occur within two weeks before or after the estimated due date, depending on various maternal and fetal factors.

Yes. An early ultrasound (typically between 8–12 weeks) can measure the baby’s growth more precisely and may adjust the due date, especially if it differs significantly from the date based on your last menstrual period.

Absolutely. IVF due dates are calculated based on the embryo transfer date, not the last period. The calculator can add 38 weeks from the day of egg retrieval or fertilization, or 36 weeks from the embryo transfer date.

Typically, your first prenatal visit should be scheduled between 6–8 weeks of pregnancy. The due date helps doctors create a care schedule for ultrasounds, tests, and monitoring throughout your pregnancy.

While the due date may be adjusted slightly based on later scans or fetal growth patterns, the original early ultrasound or LMP-based date remains the most reliable baseline for tracking pregnancy milestones.

Not necessarily. The due date is an estimate — consider it the middle of a five-week window when your baby is likely to arrive. It’s best to prepare early and stay flexible as labor can occur anytime between weeks 37–42.