—
Enter your last period start date
—
Fertile window starts
—
Fertile window ends
—
Next period
—
Take pregnancy test
Understanding Ovulation & the Fertile Window
Ovulation is when a mature egg is released from your ovary — typically 14 days before your next period starts. In a 28-day cycle, that's around day 14. In a 30-day cycle, it's around day 16.
Your fertile window is a 6-day span: the 5 days before ovulation plus ovulation day itself. Sperm can survive up to 5 days inside the reproductive tract, so intercourse during this window offers the best chance of conception.
- Day 1 — first day of period
- Days 6–13 — follicular phase
- Day 14 — ovulation (28-day cycle)
- Days 15–28 — luteal phase
Signs of Ovulation
- Clear, stretchy, egg-white-like cervical mucus
- Slight rise in basal body temperature (0.3–0.5 °C)
- Mild one-sided pelvic pain (mittelschmerz)
- Increased libido
- Positive result on an LH ovulation predictor kit
- Breast tenderness
⚕️ Medical disclaimer: This calculator provides estimates only and is not a substitute for professional medical advice. Please consult your doctor for personal reproductive-health guidance.
Frequently asked questions
When am I most fertile?
The 5 days before ovulation and the day of ovulation itself. For a 28-day cycle, this is typically days 10–15.
How accurate is this ovulation calculator?
Very accurate for regular cycles. If your cycles vary by more than 7 days, use it as a guide alongside basal body temperature charting or LH strips.
When should I take a pregnancy test?
Wait until the first day of your missed period (about 14 days after ovulation) for the most accurate result.
Can I use this to avoid pregnancy?
The rhythm method is not a reliable form of contraception. If you're trying to avoid pregnancy, please use a doctor-recommended method.
Is my data stored?
No — all calculation runs in your browser and is not saved anywhere.