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Gestational Age Calculator

Calculate your gestational age in weeks and days from your last menstrual period (LMP) or conception date. Find out how far along you are and follow your baby’s development.

This tool is informational and does not replace medical advice. Always consult your baby's pediatrician.

How does this calculation work?

The gestational age calculator determines how many weeks pregnant you are based on the date of your last menstrual period (LMP) or your estimated conception date. The most common method used by doctors is the LMP calculation, which uses the first day of your last menstrual cycle as the starting point. From that date, it counts full weeks and remaining days. A full-term pregnancy lasts an average of 40 weeks (280 days). If you choose to calculate from the conception date, the system automatically adds two weeks to align with the medical standard. This tool is useful for tracking fetal development milestones and planning prenatal appointments.

Frequently asked questions

What is the difference between calculating from LMP and conception date?â–Ÿ
The LMP (Last Menstrual Period) is the standard method used by obstetricians. It counts from the first day of your last menstrual cycle, which typically adds about 2 weeks before actual conception. If you know the exact conception date, you can use it, and the system will automatically adjust to the medical standard.
Can the gestational age change after an ultrasound?â–Ÿ
Yes. A first-trimester ultrasound is the most accurate exam for dating a pregnancy. If there is a significant difference between the gestational age calculated by LMP and the one estimated by ultrasound, the doctor may adjust the estimated due date. This correction is common and does not indicate any problem.

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