How accurate is the calculator?
Good for regular cycles (25-35 days). Irregular cycles benefit from additional tracking methods.
Health Fitness
Ovulation Calculator
Estimate ovulation with quick inputs.
Fast, practical estimates
Adjust inputs for the most useful result.
What this calculator does
An ovulation calculator predicts the day of egg release in your menstrual cycle. Ovulation typically occurs 14 days before your next period. The fertile window spans 5 days before through 1 day after ovulation.
How it works
Enter LMP and cycle length. Ovulation = LMP + (Cycle Length - 14 days).
Formula
Ovulation Day = LMP + (Cycle Length - 14). Fertile Window = Ovulation - 5 to Ovulation + 1.
Tips for using this calculator
- Track cycles for 3+ months for accuracy
- Combine with ovulation predictor kits for confirmation
- Cervical mucus changes indicate ovulation
- Basal body temperature rises after ovulation
- Irregular cycles reduce prediction accuracy
Frequently asked questions
What are ovulation signs?
Cervical mucus becomes clear and stretchy; mild pelvic pain (mittelschmerz); slight temperature rise after.
Can ovulation vary from month to month?
Yes, stress, illness, travel, and weight changes can shift ovulation by several days.