Fertility Calculator
Identify your fertile window and maximize your conception chances
(Days between ovulation and next period)
Your Fertile Window
Fertility Calendar
Key Days
Ovulation Symptoms
Clear and stretchy consistency (like egg white)
Increase of 0.2-0.5°C after ovulation
Mild discomfort on one side of lower abdomen (mittelschmerz)
Increased sex drive
How the Fertility Calculator Works
Our calculator uses the calendar method (Ogino-Knauss) to predict your fertile window based on:
- Length of your menstrual cycle: From the first day of your period to the day before your next period.
- Luteal phase: Time between ovulation and your next period (typically 12-16 days).
- Gamete lifespan: Sperm live up to 5 days, egg 12-24 hours.
Factors that can affect your ovulation:
Can delay ovulation or inhibit it completely
Infections or high fever can alter the cycle
Time zone changes affect circadian rhythms
Complementary Methods
For greater accuracy, combine this calculator with:
- Basal temperature monitoring: Take your temperature every morning before getting up.
- Ovulation tests: Detect LH hormone surge 24-36 hours before ovulation.
- Cervical mucus observation: Changes in consistency and amount.
Frequently Asked Questions
The calculator is 70-80% accurate for regular cycles. For irregular cycles, consider additional methods like ovulation tests.
Not recommended. The calendar method is 76-88% effective at preventing pregnancy. More reliable methods exist.
Factors like stress, illness or routine changes can alter ovulation. The body isn't an exact clock.
