Exact calculation of the due date
Calculating an accurate due date is an important first step in pregnancy. The calculation of the estimated due date (EDD) is based on the day of the date of ovulation and fertilization. The EDD can be calculated by adding 266 days to the day of ovulation/fertilization.
Pregnancy, on your own terms
Get expert guidance and personalized insights on your path to getting pregnant and through every week of your pregnancy.
Download appThe first step is to know the first day of your last menstrual period and the length of your menstrual cycle. Enter the date of the first day of the last menstrual period and your average cycle length. Alternatively, you can also enter the day of ovulation, the weeks and days of the pregnancy on ultrasound, or the IVF egg or embryo transfer date.
The due date calculator will then calculate the exact date the baby will be due, as well as other important events such as the date of implantation, when the baby will start moving and dates for important tests like amniocentesis, ultrasound, or glucose screen.
Get our Childbirth Course to plan for your big day including how to identify true labor, pain relief, natural birth options and more!
How many weeks am I and why is it important?
Your pregnancy weeks help determine blood tests, ultrasound examinations, and more importantly when you can expect your baby to be born. They also help you identify certain situations to learn what is normal and when to have procedures done. What is normal at 26 weeks may not be normal at 32 weeks. Also, tests that should be done at 20 weeks but are done at 16 weeks could be interpreted incorrectly.
How can I calculate important week-by-week information throughout my pregnancy?
This pregnancy calculator helps you find out exactly how many weeks pregnant you are right now, details your baby's development, and precisely what is happening to your body at the moment. Just enter your pregnancy due date or other information to create and calculate a personalized weekly and daily pregnancy calendar. The babyMed Monthly Pregnancy Calculator and Calendar is a week-by-week pregnancy calculator and calendar with information for each day of your pregnancy.
To create a Week-By-Week calendar choose from the following options:
- Weekly Count: Follow new developments in weeks and days
- Daily Countup: Count up how many days you are into your pregnancy
- Daily Countdown: Count down your days left until your due date
- Fetal Weight: Available in ounces or grams
- Ultrasound measurements: BPD, FL, HC, AC
Track implantation
This calculator also lets you know the day when you can expect implantation (the day that the embryo attaches to the lining of the uterus).
Calculate the best days to have sex
Enter the exact date of the first day of your last menstrual period and we will calculate the best days to have sex. The calculator will let you know the 5-6 fertile days to improve your chances of getting pregnant.
How many weeks am I?
Enter first your last period or due date, and we will tell you automatically how far along you are today. If you want to know how far along you are on a certain date, enter that date next and we will calculate next how far along you are.
Get pregnancy alerts and updates about your baby's development!
Why is babyMed not using "conception date"?
We are not using the terminology "conception" because the definition of conception is unclear and potentially confusing. The word "conception" has different definitions and meanings:
- One definition of conception is that conception is the same day as the day of fertilization, the time you ovulate and when the sperm meets the egg.
- Another definition of conception is that conception is the same day as the day of implantation which happens on average 9 days after ovulation/fertilization with a range of 6-12 days.
- Another definition of conception could be the day that your pregnancy test is first positive.
Using "ovulation date" or "fertilization date" are more precise descriptions of what's happening with the pregnancy and avoid confusion, they are more clear because both ovulation and fertilization usually happen on the same day, within 12-24 hours of each other.
How about IUI or intrauterine insemination?
Intrauterine insemination (IUI) is a procedure that puts sperm directly inside your uterus with a small catheter bypassing the vagina and cervix. IUI is usually done within a day prior to or on the day of ovulation. For practical purposes, the day of IUI can be considered the same day as ovulation and fertilization.
Find out why estimating the correct pregnancy due date is important.
Tracking last menstrual period (LMP)
The LMP is the date of the first day of your last menstrual period. It is the first day that your last menstrual cycle began. It is the first day that you see bright red blood, not just a little brown spotting. You should keep track of your LMP each month, either electronically, online, or at home in a calendar. That is the date you use when entering the LMP.
Am I ovulating?
If you don't know the exact date of ovulation, then use our ovulation calculator to the approximate first day of your last menstrual period in a 28-day cycle. If your cycles are longer or shorter than 28 days, then the day of ovulation may change, and this calculator takes that into consideration when calculating your estimated due date.
You can also use this calculator as a reverse due date calculator to find out when you became pregnant. Just enter your due date and we will calculate the estimated day of conception. In addition, you'll get a range of dates that you may have become pregnant.
How else can a conception calculator be used?
Conception calculator use differs from one woman to the next. If a woman has had unprotected sex with more than one man, she may want to use the conception calculator to give her an idea who the father may be. However, if there is no menstrual cycle between the bouts of unprotected sex, a conception calculator will not effectively reveal paternity. Only a paternity test will reveal the true father of the child in this case.
How accurate is a conception calculator?
There is no way of knowing the exact date of conception unless a woman tracks her cycle knows the exact day of ovulation and has unprotected intercourse only once per cycle. However, you can make an estimated guess! The conception calculator will give you an estimated date of the probable time when conception occurred.
Could the conception calculator be wrong?
Yes, a conception calculator can be wrong. Ultrasounds can also be wrong as can home pregnancy tests. There is no perfect system for estimating an exact conception date unless intercourse happened only once between menstrual cycles.
Why does the ultrasound give a different due date from the conception calculator?
A conception calculator uses the first day of the last menstrual cycle to determine the probable date of conception. Ultrasound uses the size of the fetus to estimate gestational age. Ultrasound dating can change throughout pregnancy based on the size of the fetus, but the conception calculator will always offer the same probable date of conception based on the last menstrual cycle and length of the average menstrual cycle.
What is the difference between an online conception calculator and the “wheel” conception calculator that a doctor uses?
There is no difference between the two. The doctor uses the first day of your last menstrual cycle to estimate due date and conception date in much the same way the online conception calculator works.
All results are based on the input, so you need to know the accurate first day of their last menstrual cycle to achieve the best and most reliable results.
List of references for calculating fertility and pregnancy events
References and literature used to create the formulas for the babyMed pregnancy due date calculator.
Use the week-by-week links below for detailed information about what happens each week during pregnancy.
Don't know your due date? Use our Pregnancy Calculator to find out the exact due date, with dates for exciting pregnancy events!
