Pregnancy Due Date Conception Calculator - When Did I Conceive?

  • Conception Calculator: When did I conceive? When did I get pregnant? What is my date of conception?

BabyMed's free medically exact due date calculator and conception calculator calculates precisely your pregnancy due date. It will show you when your baby is due and when you conceived. Calculation of an accurate pregnancy due date is among the most important steps in pregnancy. 

Calculation of the best estimated due date (EDD) is based on the day of the date of ovulation and fertilization. The EDD can then be calculated by adding 266 days to the day of ovulation/fertilization. 

What is the LMP Last Menstrual Period

The LMP or last menstrual period is the time of your regular bleeding. The first day of the LMP is the first day of your menstrual cycle. That is the date you enter when entering the LMP, the first day of the LMP.

The day of ovulation

If you don't know the exact date of ovulation, then use our Ovulation Calculator (or, your due date can be calculated by adding 40 weeks (280 days) 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 condideration when calculating the EDD.
This week-by-week pregnancy calendar is very helpful to follow your pregnancy day-by-day.
This Retro Birthday Conception Calculator let's you know when someone conceived based on their birthday.

Find out why estimating the correct pregnancy due date is important. Occasionally, it may be necessary to recalculate the estimated due date EDD based on other information such as on an ultrasound that was done and showed different information than a due date based only on your last period.


You can also use this calculator as a reverse due date calculator to find out when you became pregnant. Just can enter your due date and we will calculate the exact days of conception. More importantly, we will provide the range of dates that you may have made love and got pregnant.

Please also look at the Interactive Pregnancy Wheel.

How To Use the Pregnancy Due Date and Conception Calculator

The 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 the 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 pregnancy due date calculator wil 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.

In addition to this calculator, there is also a unique and handy offline tool called the Ovulation Calendar & 9-Month Pregnancy Wheel that helps determine a woman's ovulation date and serves as a traditional pregnancy wheel after conception has occurred.

"When did I conceive?" "When did I get pregnant?" and "What is my baby's date of conception?" Use our pregnancy due date calculator and you'll know!


The conception calculator can be used to estimate the date of pregnancy conception. Conception calculators use the first day of the previous menstrual cycle to estimate the date of conception. Models are based on your menstrual cycle length and the estimated time of ovulation. Ovulation is the time when the female body is primed for conception.

How Can a Conception Calculator be Used?

Conception calculator uses differ 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. 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 and has unprotected intercourse only once per cycle. The conception calculator will give a woman 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 conception date unless intercourse happened only once between menstrual cycles.

Why does the ultrasound give a different date of conception than a conception calculator?

A conception calculator will use the first day of the last menstrual cycle to determine the probable date of conception. An 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 an obstetrician 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.

A conception calculator is a tool pregnant women can use to estimate the date of delivery or the date of conception. All results are based on input, so women need to know the accurate first day of their last menstrual cycle to achieve the best, and most reliable, results.