Gestational Age Calculator
Weeks pregnant from LMP.
Enter your values
ⓘ Live results
Results
- Gestational age
- 18 weeks 0 days
- Trimester
- Second
- Days remaining to 40 weeks
- 154
- Percent of pregnancy complete
- 45%
- Estimated fetal age
- 16 weeks
Quick answer
Gestational age counts from the first day of your last period, so it runs about two weeks ahead of conception.
How to use the Gestational Age Calculator
- 1Count days since the first day of your last period.
- 2Enter that number.
- 3Read your gestational age and trimester.
Worked example
Using the values the calculator loads with:
Inputs
- Days since last period126
Results
- Gestational age18 weeks 0 days
- TrimesterSecond
- Days remaining to 40 weeks154
- Percent of pregnancy complete45%
- Estimated fetal age16 weeks
Frequently asked questions
Why is fetal age two weeks less?
Ovulation usually happens about 14 days after your period starts.
Is an ultrasound more accurate?
Yes, especially a first trimester dating scan.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.