Tracking your cycle is about more than just dates—it's about understanding your body's internal clock. We've engineered this tool to provide the highest level of predictive accuracy.
1. The 6-Day Fertile Window
Pregnancy is technically only possible during a 6-day window each month. This includes the 5 days leading up to ovulation and the day of ovulation itself. This is because sperm can survive for up to 5 days inside the reproductive tract, waiting for the egg to be released.
2. Luteal Phase vs. Follicular Phase
A menstrual cycle has two main parts:
- Follicular Phase: Starts on day 1 of your period. Its length varies from month to month.
- Luteal Phase: The time between ovulation and your next period. For most women, this is a very consistent 12-14 days. This is why we calculate ovulation by counting backwards from your next expected period.
3. Secondary Fertility Signs
Beyond calculations, your body provides physical cues of peak fertility:
- Cervical Mucus: Becomes clear, stretchy, and slippery (like raw egg whites) during your fertile window.
- Basal Body Temperature (BBT): A slight dip followed by a sustained rise of 0.5-1.0 degree after ovulation.
- Mittelschmerz: Mild pelvic cramping on one side during ovulation.
Frequently Asked Questions (FAQ)
Can I get pregnant if my cycle is irregular? ▶
Yes, but tracking becomes more difficult. If your cycle varies significantly, it is best to use secondary signs like cervical mucus and basal body temperature alongside this calculator to identify your fertile window.
When exactly does ovulation occur? ▶
In a standard 28-day cycle, ovulation usually occurs on day 14. More precisely, it happens 12 to 16 days before your next period starts. This calculator uses a 14-day luteal phase estimate.
How long can sperm survive? ▶
Sperm can survive inside the female reproductive tract for up to 5 days under the right conditions (fertile cervical mucus). This is why having intercourse in the days leading up to ovulation can lead to pregnancy.
How long does an egg live after ovulation? ▶
Once an egg is released from the ovary, it lives for only 12 to 24 hours. If it is not fertilized within this timeframe, it dissolves and is shed during your next period.
What is the "Fertile Window"? ▶
The fertile window is the 6-day period including the day of ovulation and the 5 days preceding it. Intercourse during this time offers the highest statistical probability of conception.
