# Your fertile window, explained > Why there are about six days a cycle that really count – and why it’s not one magic day. Category: Fertility & TTC · 4 min read · Written by the Splash team · Sources checked October 2026 URL: https://splash.care/learn/fertility-ttc/fertile-window-explained ## Quick answer The fertile window is the roughly six days in each cycle when sex can lead to pregnancy: the five days before ovulation and the day of ovulation itself. Sperm can survive up to five days, while an egg lives for about a day. Because ovulation day varies, the window shifts from cycle to cycle. - The fertile window is about six days: five days before ovulation plus ovulation day. - Eggs live 12–24 hours; sperm can survive up to about five days. - Ovulation is about 14 days before your next period, not always day 14. - Body signs are more reliable than calendar maths, especially with irregular cycles. Here’s a fact that surprises loads of people: you can only get [pregnant](https://splash.care/learn/fertility-ttc/early-pregnancy-signs) on a handful of days each cycle. That little stretch is called your [Fertile window](https://splash.care/learn/glossary/fertile-window), and once you understand it, a lot of fertility advice suddenly makes sense. ## How long is the fertile window? Your window is set by two timers. After it’s released, an egg lives for roughly **12 to 24 hours**. Sperm are the hardier guests – they can hang around in the uterus for up to about five days. Put those together and pregnancy is possible from about five days before [ovulation](https://splash.care/learn/glossary/ovulation) through about one day after. **12–24 hrs** How long an egg survives after ovulation (Cleveland Clinic) That’s why the most fertile days are actually the two or three days **before** [ovulation](https://splash.care/learn/phases/ovulation). Sperm that are already waiting when the egg arrives have the best chance. ## When does ovulation happen in my cycle? The NHS says ovulation usually happens about 14 days before the start of your [next period](https://splash.care/tools/period-calculator) – not necessarily on day 14. If your cycle is 32 days, that’s closer to day 18. If it’s 25 days, it might be around day 11. Cycles also wobble month to month, which is why one fixed date can mislead. - Short cycle (around 24 days): window may start in the first week after your period - Typical cycle (around 28 days): window roughly days 9–15 - Long or [irregular](https://splash.care/learn/cycle-basics/irregular-cycles) cycle: body signs (mucus, [LH tests](https://splash.care/learn/fertility-ttc/lh-tests-how-to)) beat calendar maths **Myth:** You can only get pregnant on the exact day you ovulate. **Fact:** Because sperm can survive for several days, sex up to about five days before ovulation can lead to pregnancy. - **Period:** Usually outside the window – but with short cycles, the window can begin soon after bleeding stops. - **Follicular:** The window opens. Watch for wetter, slippery [Cervical mucus](https://splash.care/learn/glossary/cervical-mucus). - **Ovulation:** Peak fertility is the day or two before and the day of ovulation. - **Luteal:** Once the egg has gone (about a day after ovulation), the window has closed for this cycle. > **Splash says:** log your discharge daily for a couple of cycles. Spotting your own “egg-white days” teaches you more than any calculator! > Knowing your fertile window is great for getting pregnant. It is not a reliable way to avoid pregnancy on its own – there are no guaranteed “safe days”. See our contraception articles if that’s your goal. **Quick quiz:** Which day is usually MORE fertile? 1. Two days before ovulation 2. Three days after ovulation Answer: Two days before ovulation. The egg only lives up to about a day, so the days before ovulation – when sperm can be waiting – are the most fertile. ## Questions people ask ### What are the most fertile days? The two to three days before ovulation and the day of ovulation (Wilcox et al., 1995). Having sex every two to three days through the cycle covers the window without needing to pinpoint it. ### Can a calendar tell me my safe days? No. Because ovulation varies, there are no guaranteed “safe days” from a calendar. If you are avoiding pregnancy, use contraception. ## Sources 1. [Cleveland Clinic – Ovulation](https://my.clevelandclinic.org/health/articles/23439-ovulation) 2. [NHS – Trying to get pregnant](https://www.nhs.uk/pregnancy/trying-for-a-baby/planning-your-pregnancy/) 3. [Cleveland Clinic – Basal body temperature](https://my.clevelandclinic.org/health/articles/21065-basal-body-temperature) This is general information, not medical advice. Splash can’t diagnose. If you’re worried, talk to a GP, pharmacist or sexual health clinic. In an emergency call 999 (UK) or 911 (US).