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Pregnancy Calculator

Calculate your estimated due date with our free, accurate interactive web tool. Includes a full step-by-step mathematical guide and formula breakdown.

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Comprehensive Guide to Pregnancy Calculator

Calculate your estimated due date, current week of pregnancy, and trimester with our free Pregnancy Calculator. Simply enter the first day of your last menstrual period.

Understanding Pregnancy Timing

Pregnancy is divided into three trimesters: First (weeks 1-12), Second (weeks 13-27), and Third (weeks 28-40). Your due date is an estimate — only about 5% of babies are born exactly on their due date.

Important Milestones

Key milestones include the first heartbeat (week 6), first ultrasound (weeks 8-12), anatomy scan (week 20), viability (week 24), and full term (weeks 39-40).

Due Date Calculation (Naegele's Rule)

$$\text{Due Date} = \text{LMP} + 280 \text{ days} + (\text{Cycle Length} - 28)$$

The standard pregnancy lasts approximately 280 days (40 weeks) from the first day of the last menstrual period (LMP). Adjustments are made for cycle lengths that differ from the average of 28 days.

Numerical Example Calculation

Example Calculation: Inputting standard baseline metrics generates real-time results instantly.

Frequently Asked Questions

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