Pregnancy Calculator
Calculate your due date, current pregnancy week, trimester, and key milestones from your last menstrual period or conception date. Trusted by parents worldwide.
🤰 About the Pregnancy Calculator
A pregnancy calculator helps expectant parents determine their estimated due date (EDD), track their current week and trimester, and see key developmental milestones. The standard method — used universally by obstetricians — calculates the due date by adding 280 days (40 weeks) to the first day of the last menstrual period (LMP), a method called Naegele's Rule.
Pregnancy is divided into three trimesters: the first (weeks 1–12) covers early development; the second (weeks 13–26) is when most parents learn the baby's sex; and the third (weeks 27–40) involves final growth and preparation for birth.
📅 Key Pregnancy Milestones
Pregnancy test turns positive. Implantation complete.
Heartbeat detectable by ultrasound. Morning sickness common.
End of first trimester. Major organs formed. Miscarriage risk drops.
Anatomy scan. Baby's sex often visible. Movement felt.
Viability milestone — baby could survive outside womb with support.
Full-term. Baby ready for birth. Lungs fully developed.
🎯 Common Uses
- Calculating estimated due date (EDD) from last menstrual period
- Tracking current pregnancy week and trimester
- Planning prenatal appointments and scans
- Identifying key developmental milestones
- Calculating conception date from a known due date
- Planning maternity leave timing
- Sharing pregnancy progress with family
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Frequently Asked Questions
❓ How is the due date calculated?
The due date is calculated by adding 280 days (40 weeks) to the first day of your last menstrual period (LMP). This is Naegele's Rule — the standard method used by obstetricians worldwide since the 19th century.
❓ What are the three trimesters?
The first trimester runs weeks 1–12, the second trimester weeks 13–26, and the third trimester weeks 27–40. Each trimester marks major developmental stages for the baby.
❓ What is gestational age?
Gestational age is the age of pregnancy measured in weeks from the first day of the LMP. A full-term pregnancy is 40 weeks. Your doctor may confirm gestational age by ultrasound measurement.
❓ How accurate is the due date?
Only about 5% of babies are born on their exact due date. Most arrive within 2 weeks before or after. The due date is a reliable estimate, not a guarantee. Ultrasound dating in the first trimester can refine accuracy.
❓ What is a premature birth?
Premature (preterm) birth occurs before 37 weeks. Babies born before 28 weeks are very preterm. Full-term is 39–40 weeks; late-term is 41 weeks. Always consult your healthcare provider for medical guidance.
❓ When does morning sickness start?
Morning sickness typically begins around weeks 6–8 and usually eases by weeks 12–14. It is caused by rising hCG hormone levels. Some women experience nausea throughout pregnancy (hyperemesis gravidarum).