Calculate your baby's due date based on your last period, conception, or IVF date.
Estimated Due Date
A pregnancy calculator helps estimate your due date, pregnancy week, and baby development timeline based on your last menstrual period (LMP), conception date, or IVF transfer. Most pregnancies last around 40 weeks (280 days) from the first day of your last period.
Use this pregnancy calculator to check your pregnancy weeks, due date, gestational age, and baby growth timeline. It works as a due date calculator, pregnancy week calculator, and conception calculator using medically accurate formulas.
Our calculator uses standard medical methods used worldwide:
Early symptoms, fertilization, and major organ formation occur.
Baby begins moving; significant growth and development milestones are reached.
Final development and delivery preparation as the baby reaches full term.
Pregnancy weeks are calculated from the first day of your last menstrual period (LMP), not from conception. To calculate manually, count the total number of days from your LMP and divide by 7. Doctors use this method to track gestational age, even though ovulation usually happens about 2 weeks later.
The most common method is Naegele’s Rule. Add 7 days to your LMP, subtract 3 months, and add 1 year. This estimates a 40-week pregnancy (280 days). Online pregnancy calculators use this same formula for accuracy.
To know how many weeks pregnant you are, count the days from your last period to today and divide by 7. For example, 42 days equals 6 weeks pregnant. This is called gestational age and is used by doctors worldwide.
A pregnancy calculator uses your LMP, conception date, or IVF transfer date to estimate your due date. It calculates pregnancy length as 280 days (LMP) or 266 days (conception) and adjusts based on cycle length.
Pregnancy due dates are estimates. Only about 5% of babies are born on the exact due date. Accuracy depends on cycle regularity and ovulation timing. First-trimester ultrasound provides the most accurate dating.
You should take a pregnancy test after a missed period for best accuracy. Early tests may work 10–14 days after ovulation, but testing too early can lead to false negatives due to low hCG levels.