PanaKit's ovulation calculator estimates your most likely ovulation day using your last menstrual period (LMP) start date and average cycle length. It applies standard luteal-phase timing—ovulation about 14 days before your next expected period—and runs instantly in your browser. Nothing you enter is stored or sent anywhere.
Select your LMP to compute.
The tool adds (cycle length − 14) days to your LMP to estimate ovulation, based on the common clinical assumption that the luteal phase lasts about 14 days before menses. That calendar approach matches fertility-awareness and obstetric education (including ACOG and NIH pregnancy-dating resources that use a typical day-14 ovulation anchor on a 28-day cycle); your entered cycle length shifts that anchor. Results are estimates—not confirmation from ovulation tests, progesterone, or ultrasound.
With an average luteal phase, ovulation often occurs about 14 days before the first day of your next period. On a 28-day cycle that is commonly around cycle day 14 counting from LMP day 1. This calculator uses your own cycle length: estimated ovulation falls on cycle day (length − 14 + 1).
Use your best average over several months. When cycles swing widely, calendar math becomes less reliable. Pair these dates with ovulation predictor kits, cervical mucus changes, or basal body temperature if you need individual confirmation.
You can enter an average cycle length for a rough estimate, but PCOS and marked irregularity often break the fixed 14-day luteal assumption. Treat the output as educational planning only and discuss timing with your clinician or fertility specialist.
This page estimates a single likely ovulation day. For a multi-day fertile window around ovulation, use PanaKit's Fertile Window Calculator in the same Trying to Conceive group.