Ovulation Calculator
Calculate ovulation date and fertile window
Calculator
How to Use
Calculate your ovulation date and fertile window
Enter last period
Input the first day of your last menstrual period
Enter cycle length
Input your average cycle length in days
View fertile window
See your most fertile days
Track cycles
Record multiple cycles for better accuracy
Ovulation Date Formula
Ovulation Day = Next Period Date - 14 days Fertile Window = Ovulation Day - 5 to Ovulation Day
The luteal phase (ovulation to period) is consistently ~14 days. The follicular phase varies.
Frequently Asked Questions
Ovulation typically occurs 14 days before your next period, not 14 days after your last one. In a 28-day cycle, ovulation is around day 14. In a 30-day cycle, around day 16. Track several cycles to identify your pattern.
The fertile window is approximately 6 days: 5 days before ovulation plus the day of ovulation. Sperm can survive 3-5 days in the body, but the egg only lives 12-24 hours. The 2 days before ovulation have the highest conception probability.
Signs of ovulation include: basal body temperature rise (0.5-1°F after ovulation), cervical mucus changes (clear, stretchy like egg whites), ovulation predictor kit positive (LH surge), mittelschmerz (ovulation pain), and breast tenderness.
Yes, stress can delay or prevent ovulation. The body perceives stress as a threat and may suppress reproduction. Illness, travel, extreme exercise, and significant weight changes can also affect ovulation timing. Track multiple cycles for accurate predictions.