Pregnancy Due Date Calculator
Free pregnancy due date calculator. Estimate your due date from your last period, conception date, ultrasound or IVF transfer, and track gestational age, trimester and key milestone dates.
How is my due date calculated?
The standard method (Naegele's rule) starts from the first day of your last menstrual period and adds 280 days, assuming a 28-day cycle. If your cycle is longer or shorter, the estimate is shifted by the difference. The calculator also supports conception date, ultrasound and IVF methods.
How accurate is a due date?
A due date is an estimate: most babies arrive within a window of about two weeks before to two weeks after the calculated day, and only around 4-5% are born exactly on their due date. Early ultrasound dating (before 14 weeks) is usually the most accurate method.
Can I calculate my due date from conception?
Yes. Gestational age is counted from the last period, roughly two weeks before conception, so the due date equals the conception date plus 266 days. This works well if you know your ovulation or conception date precisely.
How does the IVF calculation work?
For IVF the transfer date is known exactly, so dating is very precise. A day-5 blastocyst transfer adds 261 days to the transfer date, and a day-3 embryo adds 263 days, because gestational age at transfer is already 2 weeks plus the embryo's age.
Why does the cycle length matter?
The standard 280-day count assumes ovulation on day 14 of a 28-day cycle. If your cycle is regularly longer or shorter, ovulation happens later or earlier, so the due date shifts by about one day for each day of difference from 28.
What are the pregnancy trimesters?
The first trimester runs from week 1 to week 13, the second from week 14 to week 27 and the third from week 28 until birth around week 40. The calculator highlights your current trimester automatically.
What does "viability week" mean?
Week 24 is commonly cited as the point at which a baby born prematurely has a chance of surviving with intensive medical care. It is shown as a milestone, not a guarantee, and every week after 24 further improves outcomes.
Is my data private?
Yes. All calculations run locally in your browser and no dates you enter are stored or sent anywhere. When you close the page, everything is gone.
How to Use Pregnancy Due Date Calculator
A due date calculator with four dating methods: last period, conception date, ultrasound scan or IVF embryo transfer. It estimates the due date, current gestational age, trimester and key pregnancy milestones entirely locally in your browser.
- Pick a method tab at the top: last period, conception, ultrasound or IVF transfer - the label of the date field changes to match.
- Enter the date in the date field. In last-period mode, adjust the cycle length if yours is not 28 days; in ultrasound mode, add the gestational age shown on your scan.
- For IVF, choose the embryo age in the dropdown: day-5 blastocyst or day-3 embryo, then enter the transfer date.
- Read the results panel: your estimated due date, today's gestational age in weeks and days, and how many days remain until the date.
- Check the progress bar and key dates list to see which trimester you are in and when milestones such as conception, viability week and full term fall.
Early ultrasound dating (before 14 weeks) is usually the most accurate method, so if you have an early scan date, prefer the Ultrasound tab for the tightest estimate.
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