Ovulation calculator

When’s the best time to get pregnant?

If you want to know the best time to conceive, understanding your menstrual cycle and the date that you are likely to be ovulating is key.

When was the first day of your last period?

What's the average length of your cycle?

Days

Our ovulation calculator can help you work out when you are going to be most fertile.

This calculator will give you a rough idea of when you might be ovulating. For more accurate indicators, look at the common signs of ovulating, how charting your temperature can help and how ovulation test kits work.

Ovulation usually happens around two weeks before your period starts¹, and you are most likely to conceive if you have plenty of sex in the days prior to this.

Understanding your menstrual cycle

The average menstrual cycle lasts for 28 days. Day one of your cycle is the first day of your period.

Halfway through your cycle (typically between day 13 and 15), your ovaries release an egg, which then travels along your fallopian tube to your uterus. This is known as ovulation. Your ovaries also release the hormone oestrogen, which causes the lining of your uterus to thicken in preparation to receive a fertilised egg.

An egg lives for about 12 to 24 hours after it's released. A sperm must fertilise the egg within this time in order for you to get pregnant. Sperm can live for up to 7 days inside your body.

If an egg is fertilised as it makes its passage along the fallopian tube, it then embeds itself in the lining of your uterus. This is where your embryo will grow to become a baby.

If an egg is not fertilised it breaks down. Your oestrogen levels begin to drop, causing the lining of your uterus to break down too. These then leave your body as you menstruate.

Common signs of ovulation

As ovulation approaches you may notice some physical changes. These include:

An increase in vaginal mucus, along with a change in consistency which may make it look like egg white
A slightly raised temperature
Abdominal pain
Tender breasts
Spotting
Feeling bloated

Calculating ovulation dates if you have irregular periods

Irregular periods make it very tricky to predict when you’re ovulating. If you can’t time sex around ovulation, it can help to have sex every 2 or 3 days throughout your cycle.

The Science Behind Charting Your Temperature, Powered by Nutricia

Prior to ovulation your body temperature drops a little. After ovulation, it rises by around 0.2°C2. Recording your basal body temperature (this is your resting body temperature) with a special basal body thermometer (available from larger chemists or supermarkets) before you get up each morning (or even speak), can help you establish when you’re most fertile. The few days before your temperature rises indicates the time you’re ovulating.

How do ovulation test kits work?

Ovulation test kits are another way to calculate when you’re ovulating. They work by testing for raised levels of luteinising hormone (LH), which can be detected in your urine just before ovulation3. You can find them in larger chemists or supermarkets.