Free Pregnancy Due Date Calculator

Estimate your due date from your last period or conception date, and see how many weeks pregnant you are today.

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Enter a date to estimate your due date.
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Pregnant today
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Trimester
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Days to go

Only about 1 in 20 babies arrives on the estimated due date — it's a guide, not a deadline. This estimate isn't medical advice; your provider can confirm your dates.

How to use / FAQ

Enter the first day of your last menstrual period (or your conception date) and the calculator estimates your due date and how far along you are today. Everything runs in your browser — nothing is stored or sent anywhere.

How is the due date calculated?

From your last period, the tool uses Naegele's rule: it counts 280 days (40 weeks) from the first day of your last menstrual period. If your average cycle isn't 28 days, it shifts the date by the difference, since a longer or shorter cycle moves ovulation. From a conception date, it counts 266 days (38 weeks) instead.

How many weeks pregnant am I?

Pregnancy is measured in weeks from the first day of your last period, not from conception, so you're counted as roughly two weeks 'pregnant' at conception. The tool shows your current weeks and days and which trimester that falls in, based on today's date.

When do the trimesters start and end?

This tool uses a common split: the first trimester is weeks 1–12, the second is weeks 13–27, and the third is week 28 through birth. Different sources draw the lines slightly differently, so treat the boundaries as approximate.

How accurate is the estimated due date?

It's an estimate. Only about 1 in 20 babies is born on the exact due date, and most arrive in the two weeks either side. An early ultrasound often gives a more accurate date. This is general information, not medical advice — your provider can confirm your dates.