Pregnancy Due Date Estimator

The Pregnancy Due Date Estimator works out when a baby is likely to arrive from the first day of the last menstrual period (LMP).

It applies the standard obstetric method, Naegele’s rule, which counts 280 days (40 weeks) from the LMP, and lets you fine-tune the result for your own cycle: if your cycle is longer or shorter than the textbook 28 days, the tool shifts the estimated date and the estimated conception date accordingly.

Beyond the due date itself, it tells you where you are right now.

Enter your LMP and the tool reports your gestational age in the familiar "weeks plus days" format, which trimester you are in, and how many days remain until the estimated due date — or how many days overdue you are if that date has passed.

The estimated conception date is shown too, which is handy for planning and record-keeping.

Every calculation runs locally in your browser, so nothing about your pregnancy is ever uploaded or stored.

It is a quick way to sanity-check a date, plan appointments or simply count down the weeks.

Remember that this is an estimate: only around one in twenty babies arrives exactly on the due date, and your healthcare provider may revise the date after an ultrasound scan.