A fertility calendar is a way to check and record the dates of your menstrual cycle. You can find a free online fertility calendar which allows you to record your details. Then it gives you an indication of when your next ovulation will be.
However, there is nothing here that you cannot do yourself with a simple wall calendar or diary. The questions you will be asked will just be:
- When was the first day of your last period?
- How long is your cycle?
If you know the answer to these questions, you can very easily calculate your ovulation date for yourself without the need for an online fertility calendar.
The fertility calendar takes the ovulation date as being 14 days before the start of your next period. So all you need to do to figure out the date for yourself, is mark on your calendar the date that your last period started. Then figure out when your next period is due to start, according to the usual date of your cycle. Count back 14 days from that date, and you have your predicted ovulation date.
However, this method of calculating your ovulation date is not at all accurate. First, it relies on you having a regular cycle, which many women do not have. If your cycle varies by more than a day or two each time, you cannot predict your ovulation date accurately this way.
Even for women who do have a regular cycle most of the time, you will probably find that certain factors can either delay your period or bring it on early. These factors include stress, strict diets, travel, and some illnesses. All of these factors can affect your ovulation date too.
This method also assumes that you will ovulate exactly 14 days before the start of your next period. This is also something that can vary in different women or during different cycles, although not usually as much as the length of the cycle.
So altogether, this is a very unreliable way of trying to predict the date of your ovulation. There are much better ways than using a fertility calendar.
If you want to understand the cycles of your own body and know with more accuracy when you are likely to get pregnant, try other methods such as charting your temperature or using an ovulation test kit. The kit measures the levels of luteinizing hormone in your urine each day, and this is probably the best method of measuring your fertility.
Even if you do have a regular cycle, it is a good idea to track your ovulation in relation to your menstrual periods for at least a couple of months using either a thermometer or a urine test kit. This will show you whether you do in fact ovulate 14 days before the start of your next period.
You might find that you regularly have a 30 day cycle with ovulation 13 days before your next period starts, for example. Then you can use your own actual data to predict your ovulation dates for the future. This will give you a little more accuracy when using a fertility calendar.