Pregnancy Calculator

Find your estimated due date and conception window based on your last menstrual period.

Estimated Due Date

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Conception Window

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Current Week

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Pregnancy Milestones

This calculator uses Naegele's rule: LMP plus 280 days. It accounts for your cycle length to estimate ovulation and conception dates more accurately.

Pregnancy is divided into three trimesters of about 13-14 weeks each. Use this calculator to track your progress.

Simplified due date calculation.

Detailed fertility window analysis.

How is due date calculated?

Due date uses Naegele's rule: last menstrual period (LMP) plus 280 days (40 weeks). Our pregnancy calculator applies this standard method.

How do I calculate conception date?

Conception typically occurs 14 days after LMP (ovulation). Subtract 14 days from estimated due date for approximate conception date.

What is the most accurate way to calculate due date?

LMP method is standard. First-trimester ultrasound is more accurate if dates are uncertain. Use our calculator and consult your healthcare provider.

Can I calculate pregnancy without knowing LMP?

Without LMP, use conception date plus 266 days, or IVF transfer date. Our calculator works with either date.

Why is due date an estimate?

Only 5% of babies are born on their due date. Normal range is 37-42 weeks. Factors include ovulation timing and individual variation.

How accurate is a pregnancy calculator?

LMP-based calculators are accurate within 7-14 days. First-trimester ultrasound dating is more precise when available.