🌸 Ovulation & Fertile Window Calculator
Estimate your likely ovulation day, fertile window, next period, and due date if conception occurs.
📅 Enter Your Cycle Details
📊 Your Results
🥚 Next Ovulation
Most fertile day
💕 Fertile Window
Best days for conception
🩸 Next Period
Expected start date
👶 Due Date (if pregnant)
Estimated delivery
🔍 Ready to Calculate
Enter your cycle details and click calculate to see your personalized fertility calendar
📖 How to Use This Calculator
🎯 Step-by-Step Instructions
- Enter your last menstrual period (LMP): Select the first day of your most recent period
- Set your cycle length: Count days from the first day of one period to the first day of the next (typically 21-35 days)
- Luteal phase (optional): The time between ovulation and your next period (usually 12-16 days)
- Choose projection period: How many months ahead you want to see predictions
- Click “Calculate”: Get your personalized fertility calendar instantly
🔍 Understanding Your Results
🥚 Ovulation Day
Your most fertile day when the egg is released. Best chance of conception within 12-24 hours.
💕 Fertile Window
6-day window including 5 days before ovulation plus ovulation day. Sperm can survive up to 5 days.
🩸 Next Period
Expected start date of your next menstrual cycle based on your average cycle length.
👶 Due Date
Estimated delivery date if conception occurs during this cycle (280 days from LMP).
💡 Tips for Best Results
- Track your cycles: Keep a record for 3-6 months to determine your average cycle length
- Note cycle variations: Stress, illness, travel can affect timing
- Use additional methods: Consider basal body temperature, cervical mucus, or ovulation tests
- Regular cycles work best: This calculator is most accurate for women with regular 21-35 day cycles
- Consult professionals: Always discuss family planning with your healthcare provider
⚠️ Important Disclaimers
- Estimates only: This tool provides predictions based on averages, not guarantees
- Individual variation: Every woman’s cycle is unique and can vary month to month
- Not contraception: Do not use this calculator as a birth control method
- Medical conditions: PCOS, irregular cycles, or hormonal issues may affect accuracy
- Seek medical advice: Consult healthcare providers for fertility concerns or family planning
❓ Frequently Asked Questions
How accurate is this calculator?
The calculator is most accurate for women with regular cycles. It uses the standard method of subtracting 14 days from cycle length to estimate ovulation, which works for about 70% of women.
What if my cycles are irregular?
For irregular cycles, this calculator may be less accurate. Consider tracking your cycles for several months and using additional fertility signs like basal body temperature or ovulation predictor kits.
Can I use this for birth control?
No, this calculator should not be used as a contraceptive method. The rhythm method has a high failure rate. Use reliable contraception if you want to prevent pregnancy.
What’s the difference between ovulation day and fertile window?
Ovulation day is when the egg is released (most fertile 12-24 hours). The fertile window includes 5 days before ovulation because sperm can survive up to 5 days in the reproductive tract.