1. Baby
  2. Conception
  3. Ovulation
  4. Ovulation calculator
Ovulation calculator

Using an ovulation calculator can be a very useful tool in identifying your fertility window if you’re trying to conceive. Predicting ovulation and knowing more about the fertility window can also be used to avoid conception. It can be helpful for women to know when they are likely to ovulate. As a way of building body awareness or as a tool to help boost their chances of conceiving, becoming ovulation aware is a good skill. After all, over the course of a woman’s reproductive lifetime, ovulation can occur as many as 400 or more times, so there is plenty of opportunity to practice.

Bear in mind even women who are highly tuned into their body’s cycles can miss the signs that they are about to ovulate. Far from being exact, ovulation prediction weighs up the odds and at best, provides a reasonably accurate idea of the most fertile days. This is why most ovulation predictors come with a covering disclaimer – there are no guarantees. Most are described as a “best guess”, a harmless means of boosting the odds of falling pregnant.

Our easy-to-use Ovulation Calculator (below) will help you predict your prime time for conceiving a baby. Learn about the different phases of yourovulation cycle, how yourtemperaturecan alert you to ovulation and other interesting and useful facts.

The ovulation calculator is a great tool – especially when used while watching for yoursigns of ovulation.

Enter the relevant dates for you and click ‘calculate’

Ovulation calculator

Wondering when to conceive? Find out about the different phases of your ovulation cycle and predict your prime time with this easy tool.

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Note: This calculator provides an estimate to calculate your fertile window based on the information you provide. It may not be accurate. Seek advice from a medical professional if you are trying to conceive.

How can I tell if I’ve ovulated?

Each month an egg is supported towards maturity by the action of hormones on the ovarian follicle in which it rests. Generally a new egg ruptures and is released mid-cycle; around day 14-15 after the first day of the last normal period. If the egg is fertilised and implants in the uterus, there will be no period. If fertilisation does not occur, then the uterine lining and egg are shed in the next period, around 14 days later.

How can I tell my most fertile days?

The most common and easiest method of detecting ovulation is to use a monthly calendar. Mark the first day of your menstrual period and when bleeding stops. Doing this for a couple of months will help you to understand your own patterns and the cyclic, generally predictable nature of menstruation.

Although the average length of a menstrual cycle is 28 days, this can vary between individual women. Many women have shorter or longer cycles.

It is important to look for physical changes which can show you’ve ovulated, or are about to. Predicting your most fertile days will help to increase your chances of conceiving.

When Should We Try?

Having intercourse just prior to, or at the time of ovulation will maximise your chances of conceiving a baby. There is only a small fertility window – twelve to twenty four hours, where the egg is viable and capable of fertilisation. Taking your basal body temperature first thing in the morning can also give you some clues as to your most fertile days.

Many women also experience ovulation symptoms such as changes in their vaginal mucous and an increase in their libido.

Sperm are much more robust than eggs and can survive for up to five days after ejaculation. Fertilisation normally occurs in one of the fallopian tubes. As soon as the egg has been fertilised, a signal is given off to the other sperm not to waste their efforts, there has already been a lucky winner.

For more information see conception and getting pregnant.


When should I take an ovulation test?

If you know the date your last period started and the general length of your cycles, you can take an ovulation test. This will help you to detect your own, individual fertility window.

How do I calculate my ovulation cycle with irregular periods?

Though it can be hard, you can still enter the date of your last period and the lengthy of your average cycle. Keeping a record of your basal temperature will also help you predict your most fertile days.

Are ovulation calculators accurate?

Some women find ovulation calculators a great tool to predict their most fertile days. For women who have regular, 28 day cycles and are well and healthy, an ovulation calculator can be very useful. Remember though, they aren’t a guarantee of predicting the most fertile period.

Written for Huggies by Jane Barry, Midwife and Child Health Nurse on 26/04/20.