Your fertile window, calculated from your cycle — not a generic 28-day default. No signup, no fluff, everything stays in your browser.
Your fertile window
Ovulation lands about 14 days before your next period — that's true even when cycles aren't 28 days.
–estimated ovulation
The window is wider than the day
An egg lives about a day; sperm live up to five. Test strips catch the LH surge 1–2 days before ovulation — they confirm what a calculator can only estimate.
These are estimates from cycle math, not a diagnosis. Irregular cycles, PCOS, recently stopping hormonal birth control, and breastfeeding all shift ovulation — strips, basal temperature, or a doctor can confirm what a calculator can't. Not medical advice.