Free Tool · Yogacruz
Pregnancy Week Calculator
Find out how many weeks pregnant you are, your estimated due date, current trimester, and what's happening in your baby's development this week — based on your last menstrual period, conception date, or known due date.
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Estimate uses standard obstetric dating (Naegele's rule / 280-day gestation from LMP, adjusted for cycle length). Actual due dates vary — only about 5% of babies arrive exactly on the estimated date. Confirm dating and monitor your pregnancy with a qualified healthcare provider.
Frequently Asked Questions
How is my due date calculated?
Using Naegele's rule: 280 days (40 weeks) are added to the first day of your last menstrual period, adjusted for your average cycle length if it differs from the standard 28 days. If you enter a conception date instead, 266 days (38 weeks) are added to that date.
How accurate is a pregnancy calculator?
LMP-based calculations are a widely used starting estimate, but only about 5% of babies are born on their exact estimated due date — most arrive within two weeks before or after. An early ultrasound provides more accurate dating.
When does each trimester start?
The first trimester runs from week 1 to the end of week 13, the second trimester from week 14 to the end of week 27, and the third trimester from week 28 until birth, typically around week 40.
