Pregnancy Calculator
Due date and weeks pregnant
Use this when you need a fast, accurate result — no sign-up, works entirely in your browser.
Estimated due date—
Current pregnancy—
How to Use
- Enter your details into the fields above.
- Click the calculate button to get your result instantly.
- Use the clear button to start a new calculation.
Example
- First day of last period: 2026-01-01 → Estimated due date 2026-10-08
- First day of last period: 2026-06-01 → Estimated due date 2027-03-08
Formula
Naegele’s rule: due date = first day of the last menstrual period + 280 days (40 weeks). Only a minority of babies arrive on the exact due date — anything from 37 to 42 weeks is considered full term. Pregnancy is dated from the last period, not from conception, which is about two weeks later.
About Pregnancy Calculator
Due date and weeks pregnant. This free online tool gives you fast, accurate results without registration or downloads.
Everything runs locally in your browser, so your data is never uploaded or stored — privacy first.
Frequently Asked Questions
Is the Pregnancy Calculator free to use? +
Yes, it is completely free with no registration or download required.
Is my health data private? +
Yes. All calculations happen locally in your browser. Your health information is never uploaded or stored.
Is this a substitute for medical advice? +
No. This tool provides estimates for informational purposes only and is not a substitute for professional medical advice.