Ovulation Calculator
Estimate your ovulation date, fertile window, and next expected period based on your last menstrual period and typical cycle length.
Cycle details
Time from ovulation to the next period. 14 days is typical if unsure.
Estimated ovulation date:
Most fertile window:
Next expected period:
How this is estimated
Ovulation is estimated to occur (cycle length − luteal phase length) days after the start of your last period. The fertile window covers the 5 days before ovulation plus ovulation day, since sperm can survive several days while the egg survives about 24 hours. Actual timing varies from cycle to cycle — this is an estimate, not a guarantee, and should not be used as a method of contraception.