Pregnancy Calculator
See how many weeks along you are, your trimester, and how many days remain until your due date.
PregnancyScience-backed formula
Enter your details
Fill in the fields, then calculate
Please choose a date.
Enter your cycle length.
Awaiting Data
Enter your details and tap Calculate to see your results appear here.
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ResultYour result appears here.
What This Calculator Shows
This tool tracks your pregnancy week by week. From your last period, it works out gestational age, trimester, and the days left until birth.
Key dates line up into an easy week by week timeline.
Gestational age counts from the first day of your last period, not from conception. That is the standard doctors use.
The result updates to today's date each time you calculate.
How to Use This Calculator
- Choose the first day of your last period.
- Adjust cycle length if needed.
- Tap Calculate to see your progress.
The Formula Used
Weeks along = (today − last period) / 7
Days remaining = due date − today
Days remaining = due date − today
- last period
- First day of your last menstrual period.
Understanding Your Results
First trimester
Weeks 1 to 12
Organs and systems form.
Second trimester
Weeks 13 to 26
Growth and movement begin.
Third trimester
Weeks 27 to 40
Final growth before birth.
Tips to Improve
- Attend every prenatal checkup.
- Eat well and stay gently active.
- Rest when your body asks for it.
- Note questions for your provider.
Frequently Asked Questions
No. Gestational age counts from your last period, about two weeks before conception.
Full term runs from 39 to 40 weeks, though birth from 37 weeks is considered term.
Each week brings milestones your provider monitors for healthy development.
Scientific References
- American College of Obstetricians and Gynecologists. (2017). Methods for estimating the due date. Committee Opinion No. 700.
- Spong, C. Y. (2013). Defining term pregnancy. JAMA, 309(23), 2445–2446.
- World Health Organization. (2016). WHO recommendations on antenatal care.