Ovulation Calculator Am I ovulating?
Read time: 2 minutes
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.
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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.
Our ovulation calculator can help you work out when you are going to be most fertile.
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.
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.
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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.
1. NHS. (2014). How can I tell when I’m ovulating? Available from: https://www.nhs.uk/chq/Pages/982.aspx?CategoryID=50[Accessed July 2015]
2. Fertility Education & Training. (2011). Charting your fertility cycle. http://www.fertilityet.org.uk/pdfs/Charting-Your-Fertility-Cycle.pdf[Accessed July 2015]
3. Patient. (2015). Natural family planning. http://patient.info/health/natural-family-planning [Accessed July 2015]
Last reviewed: 23rd September 2019
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