Ovulation Calculator

It estimates ovulation using your last period's start date and average cycle length. Ovulation typically occurs about 14 days before your next period — this is a population average for the luteal phase, which research shows can genuinely vary roughly 11 to 17 days between cycles and between individuals, even when otherwise healthy.

This is a general estimate based on average cycle patterns, not a personalised measurement. Actual ovulation timing can vary due to stress, health conditions and cycle irregularity — this is especially true for irregular cycles or conditions like PCOS, where "cycle length" itself isn't stable. An ovulation test kit measures your actual LH hormone surge for a far more precise result.

The fertile window is the days leading up to and including ovulation when conception is most likely — typically the 5 days before ovulation plus the day of ovulation itself.