Based on the first day of your last period, the average number of days in your
menstrual cycle, and your average luteal phase length, the
ovulation calculator predicts
ovulation dates and fertile days. The predicted ovulation date
and fertile days in each menstrual cycle are approximate dates only; this ovulation calculator is intended for use
by those with regular cycles.
The luteal phase of the menstrual cycle is the number of days between
ovulation (release of an egg from the ovary) until the day before your next
menstrual period starts. For many women with regular menstrual cycles, the luteal phase is
generally from 10 to 16 days, with 14 days being the average length. If you know
your luteal phase length (because you've either
charted your fertility cycles
in the past, or have used ovulation prediction kits), you can specify it in the entry
field on the criteria screen; otherwise, you can leave 14 (the average) as the
default luteal phase length, which is what most other ovulation calculators automatically use.