Ovulation & Fertility Tracker — 6-Month Fertile Window Planner with BBT Logging

Free online ovulation and fertility tracker built for couples who are trying to conceive (TTC). Enter the first day of your last period, your typical cycle length (21–35 days, default 28), and your luteal phase length (10–16 days, default 14) and get a 6-month conception plan in a single table: the exact ovulation day, the 7-day fertile window (5 days before ovulation through 1 day after — the span sperm and egg can actually meet), the two highest-probability days for timed intercourse (ovulation minus 2 and minus 1, when sperm is already waiting in the reproductive tract), and the predicted start of every upcoming period. A built-in basal body temperature (BBT) logger lets you record morning readings, draws a 6-day baseline, and flags the classical biphasic shift (three consecutive days at or above baseline + 0.3 °C) — the after-the-fact confirmation that ovulation already happened. All math runs locally in your browser: dates and temperatures are never uploaded, never logged, never sent anywhere. This is a TTC reference, not contraception — the calendar method has roughly a 1-in-4 yearly failure rate. If you have been trying for over 12 months (or 6 months over age 35), see an OB-GYN or reproductive endocrinologist.