Ovulation Calculator
A calendar-based estimate of ovulation and the fertile window
What the calculator estimates
Cycle day one is the first day of menstrual bleeding. The calculator places ovulation about 14 days before the next expected period and marks the five preceding days through one day after as a possible fertile window.
Cycle length is not a guarantee
Ovulation can shift even in usually regular cycles because of stress, illness, travel, breastfeeding, or hormonal changes. A calendar-only estimate is especially uncertain when cycles are irregular.
Use body signs as additional clues
Cervical mucus, basal body temperature, and ovulation predictor kits may provide additional information. A single sign does not confirm ovulation and does not replace medical assessment.
Not contraception or a diagnosis
Do not use this result as a reliable method of contraception. Seek medical advice for missed or unusual bleeding, severe symptoms, difficulty conceiving, or concerns about fertility.