Pregnancy Due Date Calculator
Estimate your due date and current week of pregnancy from your last period or conception date.
Due Date Calculator
Pregnancy Due Date Calculator: The Complete Guide
One of the first questions after finding out you're pregnant is usually "when am I due?" This calculator gives you a quick estimate based on standard obstetric dating methods — the same math your doctor or midwife would use as a starting point.
How Your Due Date Is Calculated
The most widely used method is called Naegele's rule. It adds 280 days (40 weeks) to the first day of your last menstrual period (LMP) — this works because pregnancy is conventionally counted from the start of your last period, even though conception happens about two weeks later.
If you know your conception date more precisely (for example, from fertility tracking or IVF), the calculator instead adds 266 days (38 weeks) to that date, since it skips the two-week gap between LMP and ovulation.
Example (LMP method):
First day of last period: January 1
Due date: January 1 + 280 days = October 8 (estimated)
How to Use This Calculator
- Choose your method: "Last Period" if you know the first day of your last menstrual period, or "Conception Date" if you know roughly when conception occurred.
- Enter the date in the field above.
- Click "Calculate Due Date" to see your estimated due date, current week of pregnancy, and trimester.
Trimester Breakdown
| Trimester | Weeks | What's Happening |
|---|---|---|
| First | Weeks 1–13 | Early development; many people experience morning sickness |
| Second | Weeks 14–27 | Often called the most comfortable stage; energy typically returns |
| Third | Weeks 28–40+ | Final growth phase leading up to birth |
Features of This Calculator
Why Your Actual Delivery Date May Differ
A due date is an estimate, not a prediction of the exact day. Only a small fraction of babies are actually born on their calculated due date — most arrive within about two weeks before or after. Due dates can also shift if an early ultrasound suggests different dating than your reported LMP, which is common and normal. Your healthcare provider will confirm and may adjust your dates as your pregnancy progresses.