Luteal Phase Calculator

The luteal phase is the second half of your menstrual cycle — from ovulation to the start of your next period. During this phase, progesterone rises to prepare the uterine lining for potential implantation.

Normal is 10-16 days, with 14 days being the most common. Unlike the follicular phase (first half), the luteal phase is relatively consistent for each individual woman, typically varying by only 1-2 days.

A luteal phase under 10 days may indicate a luteal phase defect (LPD), where the uterine lining doesn't develop enough for implantation. This can contribute to difficulty conceiving or early miscarriage. Treatment options exist — consult a fertility specialist.