15% off £25 or 20% off £35
Code:BASKET
Ovulation calculator: find out when you’re most fertile
Written byLaura Harcourt
Reviewed byHeeral Patel
Whether you’re trying to conceive or just curious to learn more about your menstrual cycle, an ovulation calculator is a simple tool that can support you with just that
Summary
1Why use an ovulation calculator?
If you’re planning to start a family, using an ovulation calculator can help you take some of the guesswork out of timing...
2How to use our ovulation date calculator
By entering in key information, like the first day of your last period and the typical length of your cycle, our calculator works to predict...
3Other ways to track ovulation
Other ways to track your ovulation include using the rhythm method, an ovulation predictor kit, tracking your body temperature (BBT)...
If you're trying to conceive or even just trying to stay on top of your menstrual cycle, we know it can sometimes feel like a guessing game.
Why use an ovulation calculator?
If you’re planning to start a family, using an ovulation calculator can help you take some of the guesswork out of timing when to have sex by estimating your fertile window.
Using an ovulation date calculator can also be a valuable tool for those who are simply looking to learn more about their period. By highlighting the different stages of your menstrual cycle, you’ll better understand the patterns and rhythms of your body, helping you better understand each day of the month.1
From follicular to luteal, each stage comes with its own signs like bloating, breast tenderness and cravings.2 So if you’re wondering why you’re bloating more at the same time each month or why your skin breaks out every few weeks, our calculator can help you learn when you might expect to see these signs.
Please note while our calculator isn’t a substitute for medical advice, it can offer you a starting point to gain a deeper insight into your reproductive health and your cycle. Plus, it’s important to remember that everyone’s cycle is different, and each one can vary depending on so many factors, from stress to hormonal contraception and conditions like PCOS.
What is ovulation?
Ovulation is the stage of your menstrual cycle when a mature egg is released from one of your ovaries.3 It’s your most fertile time and is when you’re most likely to be able to conceive.
How to use our ovulation date calculator
By entering in key information, like the first day of your last period and the typical length of your cycle, our calculator works to predict when ovulation is most likely to happen. It’s these days, plus the days leading up to this that are believed to be your most fertile time.4
The simple calendar method
Our ovulation calculator uses the ‘simple calendar method’ to estimate when you’re most fertile. It works by subtracting 14 days from your last cycle length to give you your peak fertility days, assuming that ovulation occurs 14 days before your next period.5
Every cycle is different however, and it’s impossible to pinpoint exactly when ovulation happens using just cycle lengths.6 That’s why it’s really important to keep in mind that the dates the calculator provides are just estimates and they won’t always be spot on.
Other ways to track ovulation
Some other ways to track your ovulation include using the rhythm method (which takes into account your menstrual cycle for the last 6 months), an ovulation predictor kit (OPK), tracking your basal body temperature (BBT) and monitoring your cervical mucus.6 You could also track your cycle with an app linked to a wearable device like an Oura ring or smartwatch.7
Using a fertility test like an OPK is one of the most accurate methods of predicting when ovulation will occur, as well as confirming that it has occurred.8 This is because this method measures the levels of luteinizing hormone in your body through a urine sample, which indicates when ovulation is likely to occur.10
What’s the most accurate way to track ovulation?
There’s no one tracking method that will give you spot-on results. Instead, researchers believe that combining methods is more reliable.11
Try combining tracking methods, like our calculator, with alternatives like ovulation predictor kits, basal body temperature tracking and cervical mucus monitoring for more reliable predictions.11
What are the symptoms of ovulation?
So, you’ve estimated when you might be ovulating, but what are some of the signs to keep an eye out for when you’re in this phase of your menstrual cycle?
While it’s important to remember that every person and every period are different, some ovulation signs that you might experience include:9
- Mild pelvic pain
- Increased libido
- Clear, stretchy discharge (like egg whites)
- A slight rise in basal body temperature after ovulation
FAQs
Ovulation itself is really quick – the whole process of the egg being released by the ovary and travelling through the fallopian tube can happen within a 12-to-24-hour window.
However, your fertile window is thought to be around six days long, covering the five days up to ovulation and the day of ovulation itself. This window is longer as it includes the lifespan of the sperm, which can survive for up to five days.11
Yes, you can, but the chances are much lower than during your fertile window. After about 24 hours post-ovulation, the possibility of pregnancy is very low until the next cycle.10
Looking to learn how to increase your chances of pregnancy during ovulation? Here are some quick tips that could help:
- Lubricants: some lubricants can affect how well sperm swim, by reducing their motility and viability.11 Try using one which is marked as “sperm-friendly”, “fertility-friendly” or skip using one altogether if it’s comfortable
- Manage your stress: high stress levels can influence your menstrual cycle and fertility.12,13 We know it’s easier said than done but try to keep your stress levels in check with relaxation techniques like light exercise, meditation or breathwork 14
- Maintain a healthy lifestyle: both you and your partner should try to eat a balanced diet, exercise regularly and avoid smoking or drinking too much alcohol to keep your body healthy15
- Up the frequency: aim to have sex frequently, particularly if you’re ovulating, to maximise the chances of sperm meeting an egg18
- Try a pre-natal: taking a pre-natal vitamin with folic acid and zinc regularly for at least a month before trying to conceive16
- Medical advice: consult your GP or a healthcare professional for personalised advice and address any fertility concerns you might have, particularly if you have been trying to conceive for over a year18
Disclaimer - This tracker is for cycle tracking purposes only. If you are concerned about your health, please speak to a healthcare professional. If you notice irregular or unusual symptoms, we recommend you speak to a healthcare professional. The ovulation tracker is a wellbeing tool to support self-navigation. It is not a medical device and should not be used as contraception or diagnosis. Please consult a healthcare professional if you have any health concerns.
1. Kelly BG, Habib M. Missed period? The significance of period-tracking applications in a post-Roe America. Sexual and Reproductive Health Matters [Internet]. 2023 Sep 8 [cited 2025 Aug 11];31(4). Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC10494721/
2. Thiyagarajan DK, Basit H, Jeanmonod R. Physiology, Menstrual Cycle [Internet]. Nih.gov. StatPearls Publishing; 2024 [cited 2025 Aug 11]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK500020/
3. NHS. Menstrual cycle: animation [Internet]. nhs.uk. 2018 [cited 2025 Aug 11]. Available from: https://www.nhs.uk/conditions/periods/fertility-in-the-menstrual-cycle/
4. Wilcox AJ. The timing of the “fertile window” in the menstrual cycle: day specific estimates from a prospective study. BMJ [Internet]. 2000 Nov 18 [cited 2025 Aug 11];321(7271):1259–62. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC27529/
5. Johnson S, Marriott L, Zinaman M. Can apps and calendar methods predict ovulation with accuracy? Current Medical Research and Opinion. 2018 May 25;34(9):1587–94. Available from: https://www.tandfonline.com/doi/pdf/10.1080/03007995.2018.1475348/
6. I Soumpasis, Grace B, Johnson S. Real-life insights on menstrual cycles and ovulation using big data. Human Reproduction Open [Internet]. 2020 Jan 1 [cited 2025 Aug 11];2020(2). Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC7164578/
7. Thigpen N, Patel S, Zhang X. Oura Ring as a Tool for Ovulation Detection: Validation Analysis. Journal of Medical Internet Research [Internet]. 2025 Jan 31 [cited 2025 Aug 11];27:e60667. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC11829181/
8. Su H, Yi Y, Wei T, Chang T, Cheng C. Detection of ovulation, a review of currently available methods. Bioengineering & Translational Medicine [Internet]. 2017 Feb 25 [cited 2025 Aug 11];2(3):238–46. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC5689497/
9. Owen M. Physiological Signs of Ovulation and Fertility Readily Observable by Women. The Linacre Quarterly [Internet]. 2013 Jan [cited 2025 Aug 11];80(1):17–23. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC6081768/
10. Ovulation and fertility [Internet]. Pregnancybirthbaby.org.au. Healthdirect Australia; 2024 [cited 2025 Aug 11]. Available from: https://www.pregnancybirthbaby.org.au/ovulation-and-fertility
11. Mackenzie SC, Gellatly SA. Vaginal lubricants in the couple trying-to-conceive: Assessing healthcare professional recommendations and effect on in vitro sperm function. PLoS ONE [Internet]. 2019 May 14 [cited 2025 Aug 18];14(5):e0209950–0. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC6516666/
12. NHS website. Infertility [Internet]. nhs.uk. 2017 [cited 2025 Aug 18]. Available from: https://www.nhs.uk/conditions/infertility/
13. Lynch CD, Sundaram R, J.M. Maisog, Sweeney AM, Louis GMB. Preconception stress increases the risk of infertility: results from a couple-based prospective cohort study—the LIFE study. Human Reproduction [Internet]. 2014 Mar 25 [cited 2025 Aug 18];29(5):1067–75. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC3984126/
14. NHS. 10 stress busters [Internet]. nhs.uk. 2021 [cited 2025 Aug 18]. Available from: https://www.nhs.uk/mental-health/self-help/guides-tools-and-activities/tips-to-reduce-stress/
15. NHS. Trying to get pregnant [Internet]. nhs.uk. 2020 [cited 2025 Aug 18]. Available from: https://www.nhs.uk/pregnancy/trying-for-a-baby/trying-to-get-pregnant/
16. NHS. Planning your pregnancy [Internet]. nhs.uk. 2020 [cited 2025 Aug 18]. Available from: https://www.nhs.uk/pregnancy/trying-for-a-baby/planning-your-pregnancy/
