Pregnancy Length Calculator

Calculate how long you were actually pregnant. Just enter when your baby was born, and your last menstrual period before you were pregnant, and your pregnancy length is calculated, and also compared to estimated due date based on Naegle's Rule.

Pregnancy Length Based on Your Last Menstrual Period (LMP)

Baby's Name (optional):

Baby's Birth Date:

JanuaryFebruaryMarchAprilMayJuneJulyAugustSeptemberOctoberNovemberDecember

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199019911992199319941995199619971998199920002001200220032004200520062007200820092010201120122013201420152016201720182019202020212022202320242025

Last Period before Pregnancy:

JanuaryFebruaryMarchAprilMayJuneJulyAugustSeptemberOctoberNovemberDecember

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199019911992199319941995199619971998199920002001200220032004200520062007200820092010201120122013201420152016201720182019202020212022202320242025

Member? Select last period from list on sidebar/below.

Currently pregnant or planning a baby? MyMonthlyCycles has several due date calculators and pregnancy planners too.

Starting back at MyMontlyCycles after recently having a baby?

Welcome back! Once you track your next period, you'll see a long "cycle" (ie. your pregnancy) which can throw off calculations. There's a simple solution: use Cycle Rules on My Preferences. Read more in our FAQ - how do I mark pregnancy on my period calendar and adjust my cycle length?".

Baby born before 37 weeks?

Use the Preterm Baby Corrected Age Calculator to calculate your baby's chronological age (how old since birth) and adjusted age, a metric often used in assessing developmental skills.