Why you are "two weeks pregnant" the day you conceive
Pregnancy is counted from the first day of your last period, not from conception, because that is the date most people know. Ovulation and conception happen about two weeks later, so by the time the embryo exists you are already called two weeks pregnant. Every method on this page converts to that same starting point so the count matches your clinic's.
Three ways in, one answer
- Last period: day zero is that date.
- Due date: day zero is 280 days before it. Use this once your clinic has given you a date, especially if a scan changed it.
- Conception or ovulation date: day zero is 14 days before it.
For a clinical weeks-plus-days figure from a scan measurement or IVF transfer, use the gestational age calculator. To see every week laid out with dates, open the pregnancy calendar.
Frequently asked questions
How far along am I if I know my due date?
Your due date is 40 weeks exactly, so count back. If your due date is 10 weeks away, you are 30 weeks along. The calculator does this to the day: it subtracts 280 days from the due date to find day zero and counts forward to today or any date you choose.
How far along am I based on conception?
Add two weeks. Pregnancy is counted from the last period, which is about two weeks before conception, so someone who conceived four weeks ago is six weeks pregnant. Enter the conception or ovulation date and the calculator adds those two weeks automatically.
How far along am I when I miss my period?
About four weeks. A missed period at the end of a 28-day cycle puts you at 4 weeks 0 days, even though conception was only about two weeks earlier. That is why a positive test on the day of a missed period is already called four weeks pregnant.
Which is more accurate, my dates or the scan?
An early ultrasound. If a first-trimester scan disagrees with your period-based date by more than about five to seven days, clinics use the scan date. Enter the due date your clinic gave you in the due date mode to match their count.
How far along will I be on a specific date?
Change the date in the calculator to any day, for example a wedding or a flight, and it shows the weeks and days you will be on that date, which trimester that falls in, and how close to the due date it is. Many airlines restrict flying from 36 weeks.
These calculators give estimates based on cycle averages and standard formulas. They are for general information only and are not medical advice. For anything concerning your health or pregnancy, talk to a qualified healthcare provider.