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Pregnancy is counted in weeks from the first day of the Last Menstrual Period (LMP). Full term is 40 weeks. Babies born 37–42 weeks are considered full term.

Formule

Weeks gestation = (Current date − LMP) / 7 | Due date = LMP + 280 days

Guide étape par étape

1Weeks = (Today − LMP) / 7
2Due date = LMP + 280 days (Naegele's rule)
3First trimester: 1–13 weeks; Second: 14–27; Third: 28–40
4Preterm: born before 37 weeks

Exemples résolus

Entrée

LMP 1 January, checking 1 April

Résultat

13 weeks pregnant; second trimester begins next week

Questions fréquentes

What is Weeks Pregnant?

Pregnancy is counted in weeks from the first day of the Last Menstrual Period (LMP). Full term is 40 weeks

How accurate is the Weeks Pregnant calculator?

The calculator uses the standard published formula for weeks pregnant. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

What units does the Weeks Pregnant calculator use?

This calculator works with inches, watts. You can enter values in the units shown — the calculator handles all conversions internally.

What formula does the Weeks Pregnant calculator use?

The core formula is: Weeks = (Today − LMP) / 7. Each step in the calculation is shown so you can verify the result manually.

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