Pregnancy & Due Date Calculator

Estimate your due date and how far along you are, week by week.

A free pregnancy and due date calculator — estimate when your baby is due and see how far along you are today, using the standard 40-week method. Calculate from the first day of your last period (with your cycle length), a conception date, a known due date, or an ultrasound measurement. It shows your estimated due date, current gestational age in weeks and days, your trimester, a progress bar and key milestones like the anatomy scan and full term. 100% in-browser — educational estimate, not medical advice.

Pregnancy & Due Date Calculator features

How to use Pregnancy & Due Date Calculator

  1. Pick your method

    Choose how you want to calculate: from the first day of your last period, a conception date, a due date you already know, or an ultrasound measurement.

  2. Enter the date

    Select the relevant date on the calendar. If you chose last period, you can also set your average cycle length for a more personalised estimate.

  3. See your due date

    The calculator instantly shows your estimated due date, calculated with the standard 40-week rule adjusted for your cycle where relevant.

  4. Check how far along you are

    View your current gestational age in weeks and days, your trimester and a progress bar showing how much of the pregnancy has passed.

  5. Plan around milestones

    Use the milestone list — end of first trimester, anatomy scan, viability, third trimester and full term — to plan appointments and preparation.

Frequently asked questions

How is the due date calculated?

From your last period it uses Naegele's rule — 280 days (40 weeks) from the first day of your last menstrual period, adjusted for your cycle length. From a conception date it adds 266 days. Both point to the same estimated due date.

How accurate is a due date calculator?

It's a good estimate, but only about 1 in 20 babies actually arrives on the exact due date. An early dating ultrasound is the most accurate way to confirm dates; this tool is for planning and information only.

What if my cycle isn't 28 days?

Choose the last-period method and set your average cycle length. The calculator shifts the estimated ovulation and due date accordingly, which matters most for longer or shorter cycles.

Can I calculate from an ultrasound?

Yes. Pick the ultrasound method and enter the gestational age (weeks and days) reported on the scan along with the scan date, and the tool back-calculates your dates.

Is my information private?

Completely. Everything is calculated in your browser. No dates or details are uploaded, logged or stored anywhere.

How many weeks pregnant am I?

Pregnancy is counted in weeks from the first day of your last menstrual period, not from conception — so you're already about 2 weeks 'pregnant' at conception. Enter your last-period date and this calculator shows your current gestational age in weeks and days.

What are the three trimesters?

The first trimester is weeks 1–13, the second is weeks 14–27 and the third is weeks 28 until birth (around week 40). This calculator estimates your due date and current week so you can see which trimester you're in; always confirm dates with your doctor.

Is this medical advice?

No. This calculator provides educational estimates only. Always follow your doctor or midwife for medical guidance and confirmed dating.

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