Safe Days Calculator
Quickly calculate your safe days, fertile window, and ovulation day with our free, mobile-friendly calculator based on the calendar method.
Find Your Safe Days
Enter your cycle details to get started.
Your Safe Days Results
Safe Days: Not calculated
Fertile Window: Not calculated
Estimated Ovulation: Not calculated
Use these results for natural family planning, but consult a healthcare provider for accurate guidance.
How to calculate safe days accurately
Our safe days calculator accurately and instantly estimates safe days to avoid pregnancy, fertile windows and ovulation days based on your menstrual cycle using the calendar method. This calculator is designed for regular cycles (26-32 days).
Formulas:
- Safe Days:Days 1-7 of the cycle and from the end of the fertile window to the next menstrual period.
- Fertile Window: Days (cycle length - 18) to (cycle length - 11).
- Ovulation Day: Approximate cycle length - 14.
Example:
Cycle Length: 28 days
Last menstrual period: July 1, 2025
Safe days: July 1 to 7, 2025 and July 18 to 28, 2025.
Fertile window: July 10 to 17, 2025.
Ovulation: July 14, 2025
Fertility Phases
| Phase | Description |
|---|---|
| Safe (Early) Days | Days 1 to 7: Low risk of pregnancy, menstruation usually occurs. |
| Fertile Window | Days 10 to 17 (for a 28-day cycle): High risk of pregnancy due to ovulation. |
| Safe (Late) | Post-fertile window to next menstrual period: Low risk of pregnancy. |
| Menstruation | Start of next cycle: Bleeding phase, low pregnancy risk. |
Disclaimer: This afe days calculator is 88-95% effective with perfect use and does not protect against STIs. Consult a healthcare professional for personalized advice for better result.
