Due Date Calculator
Calculate your estimated due date and track your pregnancy progress with multiple calculation methods.
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The first day of your last period before pregnancy
Accuracy Information
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Frequently Asked Questions
Which date gives the most accurate due date (LMP, conception, or ultrasound)?
Ultrasound dating, especially when performed in the first trimester (between 6-13 weeks), provides the most accurate due date estimation with accuracy within ±3 days. Early ultrasounds measure fetal development directly rather than relying on cycle assumptions. LMP dating assumes a 28-day cycle with ovulation on day 14, which may not apply to all women, making it accurate within ±7 days. Conception date is more accurate than LMP if you know the exact date, typically within ±5 days. IVF transfer dates are very precise since the exact timing is controlled medically.
How is gestational age calculated?
Gestational age is calculated from the first day of your last menstrual period (LMP), not from conception. This means pregnancy is considered to start about 2 weeks before actual conception occurs. This system is used because the LMP date is usually more reliably known than the exact conception date. A full-term pregnancy is 40 weeks gestational age, which equals 38 weeks from conception. Gestational age is expressed in weeks and days (e.g., 12 weeks 3 days) and is used by healthcare providers to track fetal development milestones and plan prenatal care.
Medical Disclaimer
This due date calculator provides estimates for educational purposes only. Only about 5% of babies are born on their exact due date, with most births occurring within 2 weeks before or after the estimated date. Your healthcare provider may adjust your due date based on ultrasound measurements or other factors. This tool should not replace professional prenatal care or medical advice from qualified healthcare providers.