Click to show tips
Try an Example
Pick a scenario to see how the calculator works, then adjust the values
Due Date from LMP
Calculate the due date using the first day of the last menstrual period (10 weeks ago).
Key values: LMP method · 28-day cycle · Singleton
First Trimester Check
A pregnancy at approximately 8 weeks from conception date.
Key values: Conception method · 8 weeks ago · First trimester
Ultrasound Dating
Calculate timeline from an ultrasound performed at 12 weeks, 3 days.
Key values: Ultrasound method · 12w 3d at scan · 4 weeks ago
IVF Transfer Timeline
Estimate due date from a day-5 embryo transfer completed 14 days ago.
Key values: IVF method · Day-5 transfer · High confidence dating
This calculator is also known as Gestational Age Calculator.
Read the complete guideUnderstanding Gestational Age
Gestational age is measured from the first day of your last menstrual period, not from the day of conception. This is why it's often about two weeks more than "fetal age".
Examples
Pregnancy Timeline Example
Maria's last period was 10 weeks ago. Her gestational age would be:
10 weeks pregnant, which is in the first trimester.
Key takeaway: The first trimester lasts until week 12.
What to Expect
Each week of pregnancy brings new developments for your baby.
- Track weekly changes in baby development
- Monitor pregnancy symptoms by trimester
Frequently Asked Questions about Gestational Age Calculator
Why is gestational age calculated from my last period?
This is the medical standard because the exact date of conception is often unknown, while the start of the last period is usually easier to identify.
Specialized Calculators
Choose from 4 specialized versions of this calculator, each optimized for specific use cases and calculation methods.
Method
3 CalculatorsAlternative methods and approaches
Related Calculators
6 CalculatorsMore Health calculators