Being comfortable to calculate ovulation date is a critical step for most women trying to conceive or plan a pregnancy or even sometimes avoid a pregnancy. It is possible to use very handy information about your cycle to calculate the likely date you are going to ovulate
There is currently no practical method to tell the exact moment that ovulation occurs. Similarly, it’s not possible to predict the exact date you will ovulate using calculations. Because of these limitations, it is only possible to have a range of dates that we can be certain to some degree that ovulation is going to occur. Ovulation calculators will therefore not give you a specific date but a range of dates, eg from December 20st to December 26th as your fertile period.
It is therefore of utmost importance that you understand this fact, that the dates given by these calculations and calculators are estimates only and it is possible they completely miss out on the true date.
A Simple Method
The easiest method to calculate ovulation date is by using a
very simple calculation which you can do right now! The advantage of this method is that it gives you an understanding of what is going on and keeps you in control, rather than blindly following a computerized system. I would encourage you to go through this method, even if you plan to ultimately use a calculator for better understanding.
You need just three properties of your menstrual cycle
length of your cycle
- The length of the luteal phase of your cycle. Calm down, if you don’t know it now! Its very simple. It is usually about 12 to 16 days. If you have never determined yours, you can use 14 as an approximate number. You can then read
later how to determine your luteal phase length
- The date of your last normal menstrual period
The simple math
The approximate day of ovulation= Cycle Length – Luteal Phase length
My cycle length is 32 days
Luteal phase length is 12 days
Approximate ovulation date = 32-12 = 20
That means on Day 20 of your cycle is the cycle day you are likely to ovulate. Remember it is Day 20 of your cycle, not the 20th of the month!!
The ovulation calendar
Once you have known the likely cycle day of ovulation, then you can determine what day of the month that will be and what the fertile period days will be.
If your last menstrual period was December 3rd and you will likely ovulate on Day 20 of your cycle, then the actual day of the month will be 20 days after December 3rd, which will be December 23rd. Simple, just add 3 to 20 in this case!
As noted above, since you cannot be sure it will actually be
on this exact date, it is better to give an allowance, some margin of error. If I add about 3 days before and 3 days after, it gives me a very good range of days which are likely to contain my ovulation date. In this case, it will be 3 days before December 23rd, that is December 20th and 3 days after which will be December 26th. Therefore from December 20th to December 26th, ovulation is likely to occur and these are “my fertile days”. You can choose to add 2 rather than 3.
These can be very convenient, because they do most of the work above. However, you cannot just “follow blindly”. That is why I encouraged you to use the manual method above to be sure you understand what the calculator is doing and know when to make corrections if needed.
One reliable online calculator I would recommend is the WebMD Calculator
You can also learn your body’s ovulation signs which is your body’s language to let you know ovulation is occurring. Or learn about all the different ways of predicting ovulation, besides the calculator.
Be sure to Contact Doc if you remain uncertain about what to do