Pregnancy Stage

What Trimester Am I In?

Enter your last menstrual period (LMP) date to find out which trimester you're in, how many weeks remain in it, and what to expect.

First day of your last menstrual period (LMP)

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💡 Trimester dates are estimates based on your LMP. Your provider may adjust your dates using ultrasound measurements.

Frequently Asked Questions

When does each trimester start and end?

The first trimester runs from week 1 through week 13. The second trimester spans weeks 14 through 27. The third trimester begins at week 28 and continues through birth, typically around week 40.

Can I enter my due date instead of LMP?

This calculator uses LMP. If you only know your due date, try our Weeks Pregnant or Weeks Until Due Date calculators.

Is this medical advice?

No — this tool is for informational purposes only. Always follow the guidance of your doctor or midwife.