Due date calculator, pregnancy week tracker, conception date
What is the Pregnancy Calculator?
The pregnancy works like this: it estimates the due date from the last menstrual period using Naegele's rule (LMP + 280 days) and shows current week and trimester. Everything happens on your device - the input never leaves your tab unless the tool clearly states it performs a server-side lookup.
How to use the Pregnancy Calculator
Enter the values the calculator asks for.
Double-check the unit or period next to each field (per month vs per year, cm vs m).
Read the result together with the breakdown shown beneath it.
Adjust one input at a time to compare scenarios side by side.
Features
Due date calculator, pregnancy week tracker, conception date
Instant result, no page reload
Works in any modern browser, desktop or mobile
Free with no signup
Common mistakes to avoid
Mixing units or periods between fields
Rounding inputs before the final calculation
Treating estimates as guarantees for major decisions
Examples
Input
Result
LMP 12 June 2026
Estimated due date 19 March 2027 · currently week 14, second trimester
Best used for
Getting a reliable answer for pregnancy without installing an app
One-off tasks done in under a minute from any device
Checking results before committing them to something important
Working on a phone where desktop software is unavailable
Privacy
Calculations run in your browser. Enter only what the calculation needs.
Frequently asked questions
How accurate is the due date?
Only about 4% of babies arrive exactly on the estimated date; term is anywhere from 37 to 42 weeks. Early ultrasound dating is more precise than LMP.
How is the due date calculated?
Naegele's rule: last menstrual period plus 280 days, assuming a 28-day cycle with ovulation on day 14. Cycles shorter or longer than 28 days shift the real date by the difference.
How accurate is the estimate?
Delivery within a week either side is typical - only about 4% of babies arrive exactly on the estimated date, and ultrasound dating in the first trimester is more precise than LMP math.