Free pregnancy calculator: enter your last menstrual period to estimate current weeks, days and trimester. An estimate only, not medical advice. 100% Local
How to Use the Pregnancy Calculator
Enter the first day of your last period and, optionally, a reference date, then press Calculate Weeks. The result updates as you type.
How it works
Pregnancy may be dated from the last menstrual period, a common clinical convention.
Weeks and leftover days are counted from that date to the reference date.
Trimesters are shown as weeks 0–12, 13–27 and 28 onwards.
Features
Current pregnancy week and leftover days
Trimester shown as stage one, two or three
Uses a reference date you can set
All processing runs locally in your browser. Your data is not uploaded to any server.