There are various ways to estimate the day of ovulation.
You can estimate your date of ovulation and conception from the length of your menstrual cycle if this is fairly regular.
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The day of your definitive positive reading is the day of the biggest increase in your LH.
This "LH surge" triggers ovulation and predicts it is likely to occur 24 to 36 hours later.
However, you can use various factors and knowledge about reproduction to help narrow down the date to within one to five days if your cycles are regular.
The accuracy of estimating your date of conception depends on several factors about your menstrual cycle and ovulation, as well as facts about the egg and the sperm.
By these facts: A conception date calculator can make it easier to figure out your date.
The calculator below works for you if your menstrual cycles are regular and are between 24 and 38 days long.
If you tracked these changes, the day before your mucus changed to a thick, tacky, cloudy, dried-up mucus was the day of ovulation, and your likely date of conception.
The day of ovulation, your mucus would have been at its most thin and watery, as well as clear and stretchy like egg white. Once your doctor or midwife gives you your due date, count 38 weeks back on a calendar to find your most likely conception date.
If your cycle lengths vary a lot, your results might not be accurate.
The calculator assumes ovulation occurs 14 days before the date of an expected period as explained in the section on 'Calculation by Menstrual Cycle Length' above.
It is important to note doctors don't use the date of conception to date a pregnancy.