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Pregnancy Calculator

Calculate gestational age in weeks, estimated due date (EDD) and pregnancy trimester. 100% free.

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First day of your last period

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Pregnancy Calculator — Due Date and Weeks

The Pregnancy Calculator is a free online tool that estimates your baby's due date, current gestational age in weeks and days, and the trimester you are in based on the date of your last menstrual period (LMP). The calculation follows the Naegele's rule — the same method used by obstetricians worldwide — which estimates the due date as 280 days (40 weeks) from the first day of the last menstrual period. No registration required, instant results.Enter the first day of your last period and the calculator instantly shows: your estimated due date, current gestational age (weeks + days), which trimester you are in (first: weeks 1-12, second: weeks 13-27, third: weeks 28-40), probable conception date (approximately 2 weeks after LMP), and a week-by-week pregnancy timeline highlighting key developmental milestones. The tool also shows when to expect important prenatal checkups and screening tests based on gestational age.Expectant parents use this to track pregnancy progress and prepare for the arrival. Women trying to conceive calculate their fertile window and potential due dates. Healthcare providers use it as a quick reference during consultations. Family members plan baby showers and support around the estimated due date. Please note that this is an estimation tool — actual due dates can vary, and only 5% of babies are born on their exact due date. Always consult your healthcare provider for medical advice.Pregnancy Calculator is part of the facilita.tools health and wellness toolkit. Available in Portuguese, English, and Spanish, optimized for desktop and mobile.

Frequently Asked Questions

How is the due date calculated?
The due date is estimated by adding 280 days (40 weeks) to the first day of your last menstrual period. This is the same method used by most healthcare providers.
How accurate is this calculator?
Only about 5% of babies are born on their exact due date. The estimate gives a 2-week window around the date. Always consult your healthcare provider for medical advice.
What is the difference between gestational age and fetal age?
Gestational age is counted from the first day of the last menstrual period (LMP), which is about 2 weeks before conception. Fetal age (or conceptional age) starts from the actual date of fertilization. Medical professionals typically use gestational age, so the pregnancy is considered 40 weeks.