OvuSense logo

How to Calculate Your Ovulation Date

When you’re trying to get pregnant you need to know when you’re due to ovulate. It’s ovulation that defines what’s known as your ‘fertile window’, and if you don’t know when you’re due to ovulate, you can’t make sure you’re trying to conceive at the time when you stand the best chance of succeeding.

It’s not always easy, but it is possible to find out when you’re likely to ovulate in advance, and use that information to make better plans for starting your family!

What is Your Fertile Window?

The fertile window is the name given to the period of time in each menstrual cycle when the lifespan of sperm after ejaculation overlaps with the lifespan of an egg when it’s ejected from the ovaries in the female body. That egg remains fertile for a maximum of twenty four hours after ovulation, while sperm can last longer – as long as five days!

Added together that gives you a fertile window of up to six days – the five days before you ovulate and the day immediately afterwards. This might be shorter for you, depending on the health of both eggs and sperm, but whatever the length of the window, you need to know when you’re going to ovulate to determine when this period is.

Ovulation Calendars

If you have a very regular cycle, you can simply use a calendar to determine when you ovulate, in combination with factors like cervical mucus. Marking the date your period starts on the calendar gives you the first day of your cycle, and if you check your cervical mucus for the change that happens when you ovulate – it becomes slicker and clearer, resembling egg white – you’ll know the time you need to be targeting each month.

Ovulation Prediction Kits

If you’re finding it difficult to determine when you ovulate using the simple method above, you might need a little more help. OPKs work like pregnancy tests: they check your urine for a high concentration of LH, the luteinising hormone. This surges in your body to cause ovulation, so a high concentration in your urine is a good indicator for ovulation.

Unfortunately, not everyone has the same level of LH. If yours is particularly high or low, these tests can’t give you an accurate result: they either deliver a false positive or don’t register that you’re ovulating at all.

Basal Body Temperature

Your BBT offers an answer that’s not affected by hormone levels. OvuSense focuses on this to give you accurate predictions of when you’re due to ovulate and therefore when your next fertile window is.

You’ll need to take your temperature first thing in the morning to access this low, basal level – or, with OvuSense, let our sensor take your temperature right through the night – and plot the measurements on a graph – or use our algorithm to turn the data into a prediction you can start using immediately!