How Many Weeks Pregnant Am I?
Enter your due date or the first day of your last period below to instantly find out your current pregnancy week and day.
This page is for general pregnancy planning and date guidance only. It is not medical advice, diagnosis, or treatment. Pregnancy dates are estimates and can change after a scan or advice from your midwife, GP, or maternity team.
If you have symptoms, concerns, or questions about your pregnancy, speak to your midwife, GP, or maternity team. For urgent help, use NHS 111; call 999 in an emergency. Read how we source and review content in our editorial policy.
Build Your UK Pregnancy Timeline
Enter a date to see your week, countdown, NHS milestone windows, and practical next steps.
How is my pregnancy week calculated?
In the UK, the NHS calculates your pregnancy from the first day of your last menstrual period (LMP). This means that for the first two weeks of your pregnancy timeline, you aren't actually pregnant yet! Pregnancy typically lasts around 280 days (40 weeks) from your LMP.
Please remember that pregnancy dates are estimates. Only around 4% of babies are born on their exact due date. Your 12-week dating scan will give you a more accurate timeline.
Frequently Asked Questions
- What if I don't know my last period date?
- If you know your conception date, you can use that instead. Otherwise, your ultrasound scan will provide the most accurate estimate of how many weeks pregnant you are.
- How many months is 12 weeks pregnant?
- 12 weeks is roughly at the end of your third month of pregnancy, marking the end of the first trimester.
Sources and further reading
Checked for UK pregnancy planning guidance in July 2026.
- NHS Pregnancy Guidance
- NHS: Ultrasound scans in pregnancy
- NHS Start for Life: Pregnancy
- RCOG patient information
We prioritise official NHS and GOV.UK guidance, then relevant professional-body information where needed.
Source links are checked on the review date shown above. Your midwife, GP, maternity team, fertility clinic, or employer can give advice that is more specific to your circumstances.