Pregnancy Week & Trimester Calculator
Pregnancy week, trimester, and weeks-until-due from LMP. Not medical advice.
Result
Pregnancy week
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How to use this calculator
- Enter LMP.
- Set "as of" to today.
- Read week, trimester, and weeks-to-due.
About this calculator
Pregnancy is conventionally measured from LMP. A standard pregnancy is 280 days (40 weeks) from LMP. Trimesters: 1st (0-12 weeks), 2nd (13-26), 3rd (27-birth). Most births happen between week 38 and 42; "term" is 37+ weeks. Not medical advice — work with a qualified provider.
Frequently asked
Naegele's Rule: LMP + 280 days. Conventional in US, UK, and most of the world. Some countries use LMP + 282 days.
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