Cycle Tracking

Know Your Fertility Window

Enter your last period date and cycle length. We'll show you when you're most likely to ovulate and your fertile days.

🌙 Enter your cycle details
⚠️ This tool is for general information only. Cycle tracking is not a reliable method of contraception. Ovulation can vary due to stress, illness, hormonal changes, and other factors. Consult a healthcare provider for personalized advice.

How does ovulation tracking work?

Ovulation typically happens about 14 days before your next period — not 14 days after your last period. That distinction matters. If you have a 28-day cycle, you likely ovulate around day 14. If you have a 35-day cycle, ovulation is closer to day 21.

Your fertile window is typically the 5 days before ovulation plus ovulation day itself — sperm can survive up to 5 days inside the body, so having sex before ovulation can still result in pregnancy. This tool calculates both your estimated ovulation day and your full fertile window.

New to cycle tracking? Here's what it means

Your cycle starts on day 1 of your period. The first half (follicular phase) is when your body prepares an egg. Ovulation happens when that egg is released — usually mid-cycle. The second half (luteal phase) is fairly consistent at about 14 days for most people. Understanding this rhythm helps you know your body better, whether you're trying to conceive, avoid pregnancy, or just understand why you feel different at different points in the month.

Can this replace birth control?
No. Cycle tracking has high failure rates as contraception because cycles vary. Use it to understand your body, not as your only protection.
What if my cycle is irregular?
Irregular cycles make tracking less predictable. Use your average cycle length and know that your actual ovulation date may vary. Apps that track multiple months of data are more helpful for irregular cycles.
What's the luteal phase?
The luteal phase is the time between ovulation and your next period. It's fairly consistent at 12-14 days for most people. If your luteal phase is shorter than 10 days it may affect fertility — worth discussing with a doctor.