🌸 Conception Date Calculator
Know the day you conceived? Find your due date, current week and trimester.
Use the day of ovulation or intercourse if you tracked it. For IVF, use the IVF calculator.
Your estimated due date
Due date = conception date + 266 days (38 weeks). Only about 1 in 20 babies arrives on the exact date, and any birth between weeks 37 and 42 is considered full term. This is an estimate, not medical advice. Please confirm your dates with your doctor.
How to use this calculator
- Pick your conception date from the calendar. This is the day you ovulated or the day you believe you conceived.
- Press Calculate Due Date.
- Read your result: your due date, how many weeks and days pregnant you are today, your trimester and the days left.
- Share the result with your doctor and confirm it with an early ultrasound.
Frequently asked questions
How is the due date calculated from the conception date?
The calculator adds 266 days (38 weeks) to your conception date. Doctors count a full pregnancy as 40 weeks from the first day of the last period, and conception usually happens about 2 weeks after that, which is why the count from conception is 38 weeks.
What if I don't know my exact conception date?
Most people don't. Sperm can survive for up to 5 days and an egg lives only about 12 to 24 hours, so conception can happen a few days after intercourse. Your best date is the day an ovulation test turned positive or the day you tracked ovulation. If you have neither, use the last period (LMP) calculator, or get an early ultrasound.
Why does the calculator say I am 2 weeks pregnant on the day I conceived?
Pregnancy weeks are counted from the first day of your last period, not from conception. On the day of conception you are already about 2 weeks pregnant by this count. This is the same way your doctor counts, so the weeks here will match your medical reports.
How accurate is a due date based on conception?
It is a good estimate, but only about 1 in 20 babies is born on the exact due date. Any birth between 37 and 42 weeks is normal. If your conception date is only a guess, an early ultrasound gives a more reliable date.
Can I use this if I conceived through IVF or IUI?
For IVF, use the IVF due date calculator, because the embryo's age on the transfer day changes the count. For IUI, the day of insemination is close to the day of ovulation, so you can use that date here.
Other methods: Last period (LMP) · IVF transfer
What Is a Conception Date Calculator?
A conception date calculator is a simple tool that works out your estimated due date from the day your baby was conceived. It is useful if you tracked ovulation or know when you got pregnant. Many women also use it after a positive ovulation test or a treatment such as IUI. In short, it turns one date into a full pregnancy timeline.
How the Conception Date Calculator Works
The calculator adds 266 days, or 38 weeks, to your conception date. That is the average length of a pregnancy from conception to birth.
Doctors, however, count pregnancy from the first day of your last period. Conception usually happens about two weeks after that day. For this reason, the calculator adds those two weeks when it tells you how far along you are.
For example, say you conceived on 1 September 2026. Your due date is 25 May 2027. On the day you conceived, you are already counted as 2 weeks pregnant.
Along with your due date, the tool shows:
- how many weeks and days pregnant you are today
- your current trimester
- how many days are left
- how far you are through the 40 weeks
How to Find Your Conception Date
Most people do not know the exact day they conceived. Still, you can make a good estimate. Try these methods, starting with the most reliable:
- Ovulation test. Ovulation usually happens within a day or two after a positive test, so use that day or the day after.
- Cycle or temperature tracking. Your body temperature rises slightly after you ovulate, which shows when it happened.
- Counting back from your period. Ovulation usually happens about 14 days before your next period starts.
- Date of intercourse. Use this one with care. Sperm can live for up to five days, while an egg survives only about 12 to 24 hours. So conception can happen a few days after intercourse.
If none of these work for you, use the last period (LMP) calculator instead. You can also ask your doctor for an early scan.
Conception Date vs. Last Period Date
When your cycle is regular, both dates lead to almost the same due date. The difference is the starting point. The last period method assumes a 28-day cycle and ovulation on day 14. The conception method starts from the real event.
Therefore, if your cycle is longer, shorter or irregular, the conception date is often the better choice, as long as you know when you ovulated. Our guide on how a due date calculator works explains this in more detail.
How Accurate Is Your Result?
Your result is an estimate. Only about 1 in 20 babies arrives on the due date, and a birth between 37 and 42 weeks is considered normal. Also, a conception date that is a guess can be off by several days, and the due date will be off by the same amount.
For this reason, always confirm the date with your doctor. A dating ultrasound in the first trimester is the most reliable check. After your scan, you can compare the dates with our ultrasound due date calculator.
If you conceived through IVF, use the IVF due date calculator instead. The age of the embryo on transfer day changes the count.
What to Do After You Know Your Due Date
Once you have your date, you can start planning. First, book your first prenatal visit. Next, ask about your early dating scan. Then, check your starting weight with the pre-pregnancy BMI calculator, and track your weight gain week by week on our homepage tracker.
Try the conception date calculator above whenever you want to check your dates again. Remember that it gives an estimate and is not medical advice. Always follow your doctor’s guidance. “Thinking of the names”? Try our Baby Name Generator.