Ovulation & Fertility Tracker
Know Your Fertile Window

Ovulation typically occurs 14 days before your next period (not 14 days after your period starts). For a 28-day cycle, this is around day 14. For a 30-day cycle, it's around day 16. For a 35-day cycle, it's around day 21. The luteal phase (time from ovulation to next period) is fairly consistent at 12–16 days, while the follicular phase (period to ovulation) varies more between women.

The fertile window is the period during which intercourse can result in pregnancy. It spans the 5 days before ovulation plus ovulation day itself — 6 days total. Sperm can survive in the female reproductive tract for up to 5 days, while an egg is only viable for 12–24 hours after ovulation. The most fertile days are the 2–3 days leading up to and including ovulation day.

This calculator uses the standard calendar method based on average cycle length and luteal phase duration. It is a useful planning tool but not 100% accurate for everyone. Cycles can vary due to stress, illness, travel, and other factors. For greater accuracy, combine calendar tracking with basal body temperature (BBT) charting, cervical mucus monitoring, or ovulation predictor kits (OPKs). Never use this as a sole method for contraception.

Common signs of ovulation include: clear, stretchy cervical mucus (like raw egg white), a slight rise in basal body temperature (0.2–0.5°C), mild one-sided pelvic pain (mittelschmerz), increased sex drive, breast tenderness, and a positive ovulation predictor kit (LH surge). Tracking multiple signs together (the symptothermal method) provides the most accurate picture of your fertile window.