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ARVENRA
Pregnancy & reproductive health

Pregnancy Calculator

Gestational week, trimester and days remaining.

Start from the first day of your last period or from an estimated due date. The tool works out gestational age, trimester and progress.

Your details

From the first day of one period to the first day of the next. Default 28 days.

Typical range: 20 – 45

The values you enter are calculated in your browser only — nothing is stored or transmitted.

Fill in your details and press calculate — your result will appear here.

Formula and method

Gestational age is counted from the first day of the last menstrual period. A term pregnancy is taken as 280 days.

Formula used

Gestational age from LMP; 280-day term

Assumptions and limits

  • Dating from the last period is an estimate. A first-trimester ultrasound is the most accurate reference.

Scientific sources

  1. American College of Obstetricians and Gynecologists. “Committee Opinion No. 700: Methods for Estimating the Due Date.” Obstet Gynecol. 2017;129(5):e150-e154.

    View source

  2. American College of Obstetricians and Gynecologists. “Committee Opinion No. 700: Methods for Estimating the Due Date.” Obstet Gynecol. 2017;129(5):e150-e154.

    View source

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