Ovulation Calculator
Calculate your ovulation date and fertile window based on your menstrual cycle. Track your most fertile days for family planning.
Enter your cycle information
Average cycle length is 28 days. Normal range is 21-45 days. All calculations happen in your browser.
Frequently Asked Questions
When do I ovulate during my menstrual cycle?▾
Ovulation typically occurs about 14 days before your next period. For a standard 28-day cycle, that means around day 14. For shorter or longer cycles, the ovulation day shifts accordingly.
What is the fertile window and how long does it last?▾
The fertile window spans approximately 6 days: the 5 days before ovulation and the day of ovulation itself. Sperm can survive up to 5 days, so intercourse before ovulation can still result in pregnancy.
How does cycle length affect ovulation timing?▾
The luteal phase (ovulation to next period) is typically fixed at about 14 days. If your cycle is 35 days, ovulation occurs around day 21. If your cycle is 21 days, ovulation occurs around day 7.
How accurate is an ovulation calculator?▾
Calendar-based ovulation calculators provide estimates based on average cycle patterns. Actual ovulation can vary by a few days. For more precision, combine with ovulation predictor kits or basal body temperature tracking.
Is my data safe when using this ovulation calculator?▾
Yes. All calculations happen entirely in your browser. No personal health data is ever sent to a server.