Pregnancy Due Date Calculator

Estimate your pregnancy due date from your last period, and see how far along you are in weeks and which trimester.

Read the guide: How Your Pregnancy Due Date Is Calculated

How it works

  1. 1

    Enter your last period

    Add the first day of your last menstrual period.

  2. 2

    See your due date

    The estimate uses Naegele’s rule — 280 days from that date.

  3. 3

    Track your progress

    View your current week, days and trimester.

Instant & 100% private — nothing is uploaded

Every calculation runs locally in your browser. The measurements, dates and details you enter stay on your own device and are never sent to a server — nothing is stored, logged or shared.

Frequently asked questions

How is the due date estimated?
It adds 280 days (40 weeks) to the first day of your last period, assuming a regular 28-day cycle. Only about 1 in 20 babies arrives exactly on the date.
How accurate is it?
It is a reasonable estimate, but your clinician’s dating ultrasound — especially in the first trimester — is more accurate, particularly with irregular cycles.
Is this medical advice?
No. These calculators are for general information and education only. They are not a diagnosis or a substitute for professional care — talk to a doctor or qualified clinician about your health.