Your very own ovulation calculator.

Marking menstruating days on a calendar is but the first step of a fun and important skill that isn’t taught in schools: “mummy maths”!
Before using this calculator to calculate ovulation days, you need to know:

• the first day of your last menstrual period (LMP date),
• your cycle length (e.g. 28 days), and
• the length of your luteal phase.

The luteal phase is counted after ovulation up to either pregnancy, or the breakdown of the corpus luteum. The typical length for a luteal phase is 10–16 days, though most commonly it lasts for around 14 days