Frequently Asked Questions

Our calculator uses standard cycle length minus 14 days to estimate ovulation. For women with regular 28-day cycles, it's about 80-90% accurate.

If your cycles vary by more than 3 days, consider tracking basal body temperature or using ovulation test strips for confirmation. The tool is a starting point, not a medical diagnosis.

Your fertile window is the 6-day period ending on ovulation day. It includes the 5 days before ovulation plus ovulation day itself.

Sperm can survive up to 5 days in fertile cervical mucus, so intercourse during this window offers the best chance of conception. This is why we calculate the full window, not just one day.

Yes, but with caution. Enter your average cycle length. If your cycles range from 26-32 days, use 29 as your average.

For highly irregular cycles (varying more than 7 days), this calculator provides estimates only. Consider consulting a healthcare provider for personalized guidance.

No. All calculations happen in your browser. Your cycle data is stored only in your device's local storage.

We don't collect, store, or share any personal information. No account required. No email signup. No cloud database. Your privacy is absolute.

The calculator estimates based on dates. To confirm ovulation, track:

1. Basal body temperature (rises 0.3-0.5°F after ovulation)
2. Cervical mucus changes (clear, stretchy before ovulation)
3. Ovulation predictor kits (detect LH surge 24-36 hours before)
4. Mittelschmerz (one-sided pelvic pain during ovulation)

This tool is designed for women trying to conceive. For natural family planning or avoiding pregnancy, you need a more rigorous method.

The calendar method alone has a 24% failure rate. If avoiding pregnancy is your goal, consult a healthcare provider about reliable contraception options. Don't rely solely on this calculator.