Trimester Calculator
Estimate current pregnancy trimester, pregnancy week, due date context, and trimester date ranges.
Disclaimer: This calculator provides educational estimates only. It is not medical advice, diagnosis, contraception guidance, or a substitute for a qualified healthcare professional.
Trimester Calculator
A trimester calculator estimates which pregnancy trimester applies based on pregnancy week or date information. It can help place pregnancy timing into first, second, or third trimester context.
The trimester calculator is a simple timing companion to the pregnancy due date calculator and pregnancy week calculator.
How to Use the Trimester Calculator
- Enter the pregnancy week or date information requested by the page.
- Review the estimated trimester.
- Check the related pregnancy week and due date context.
- Use the result for general planning and conversation with your care team.
Formula Used
First trimester = through 13 weeks and 6 days
Second trimester = 14 weeks through 27 weeks and 6 days
Third trimester = 28 weeks through birth
If the calculation starts from a date, gestational age is estimated first and then mapped to a trimester.
Example
If gestational age is 16 weeks, the trimester estimate is the second trimester. If gestational age is 30 weeks, the estimate is the third trimester.
What Your Result Means
The result gives broad pregnancy timing context. It does not evaluate pregnancy health, fetal development, or individual medical factors.
Accuracy and Limitations
Trimester boundaries are general dating markers. Your clinician may use more specific dating and monitoring for care decisions.
Related Calculators
Methodology and Disclaimer
This calculator uses common trimester boundaries based on gestational age. It provides educational estimates only. It is not medical advice, diagnosis, contraception guidance, or a substitute for a qualified healthcare professional.
FAQ
When does the second trimester start?
The second trimester generally starts at week 14.
When does the third trimester start?
The third trimester generally starts at week 28.
Does trimester timing depend on due date?
Due date can be used to estimate gestational age, which then determines trimester.
Can a clinician date pregnancy differently?
Yes. Ultrasound and clinical information may adjust pregnancy dating.
Is trimester a diagnosis?
No. It is a timing category and does not replace medical care.