Pregnancy Week Calculator
Find out which week and trimester of pregnancy you are in based on your LMP date.
How to Use the Pregnancy Week Calculator
Find out which week and trimester of pregnancy you are in based on your LMP date. Enter your information in the form above and get instant results.
Medical Disclaimer: This tool is for informational purposes only. Always consult your healthcare provider for medical advice.
Frequently Asked Questions
How are pregnancy weeks counted?
Pregnancy weeks are counted from the first day of your Last Menstrual Period (LMP), not from conception. Week 1 starts on the day of your LMP.
What are the trimesters?
First trimester: weeks 1–12. Second trimester: weeks 13–27. Third trimester: weeks 28–40.
Why does pregnancy start before conception?
Dating pregnancy from LMP is standard practice because the exact day of conception is often unknown, while the period date is usually remembered.