Pregnancy Due Date
Calculator for Women
Calculate your estimated due date and track pregnancy milestones based on your last menstrual period. This free pregnancy calculator provides instant results with trimester information.
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How This Pregnancy Due Date Works
Pregnancy typically lasts 280 days (40 weeks) from the first day of your last menstrual period. This calculator uses Naegele's rule, the standard clinical method for estimating due dates. The tool also calculates your current week of pregnancy and which trimester you are in.
When Should You Use This Tool
Use this calculator after confirming pregnancy to estimate your delivery date. The due date helps schedule prenatal appointments, plan maternity leave, and track fetal development milestones. For the most accurate results, use this calculator within the first trimester.
Is This Tool Accurate and Safe
Only about 5% of babies arrive on their exact due date. Most healthy deliveries occur within two weeks before or after the estimated date. This calculator provides estimates based on average pregnancy duration. Ultrasound measurements from your healthcare provider may adjust the due date. All calculations run privately in your browser.
Frequently Asked Questions
How accurate is the pregnancy due date calculator?
This calculator estimates based on average 40-week pregnancy duration. Actual delivery dates vary. Your healthcare provider may adjust the date based on ultrasound measurements, especially in early pregnancy.
What if I know my exact conception date?
If you know your conception date, add 266 days instead of using the last period method. Conception-based calculations can be more accurate for women with irregular cycles.
Can my due date change during pregnancy?
Yes. Early ultrasounds may adjust the due date if fetal measurements differ significantly from LMP-based calculations. Trust your healthcare provider's adjusted date over calculator estimates.
What are the three trimesters of pregnancy?
First trimester: weeks 1-12. Second trimester: weeks 13-26. Third trimester: weeks 27-40. Each stage has distinct developmental milestones and maternal experiences.