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Ovulation Calculator - Fertile Days Calendar

Free ovulation calculator to find your ovulation day and fertile window. Determine the best time to conceive with our fertility calendar.

Ovulation Calculator

Find your ovulation day and fertile window

The FIRST day of your last menstrual period (when bleeding started).

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Days from first day of one period to first day of next. Average is 28 days.

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Days from ovulation to next period. Usually 14 days for most women. Use default if unknown.

Your Ovulation Calendar

Enter your values to see results

and click the "Calculate" button

What is Ovulation?

Ovulation is the natural process where an egg is released from the ovary each menstrual cycle. This egg remains viable for fertilization for 12-24 hours. Sperm can survive in the female body for up to 5 days. Therefore, the 5 days before ovulation and ovulation day itself (total 6 days) are called the 'fertile window'. Having intercourse during these days increases your chances of conception.

How to Use This Calculator

  1. Enter the first day of your last menstrual period
  2. Enter your average cycle length
  3. Optionally adjust luteal phase if you know it
  4. Click Calculate to see your fertile window

Ovulation Calculation

Ovulation = Next Period Date - Luteal Phase (typically 14 days)

Fertile window: 5 days before ovulation through 1 day after.

Frequently Asked Questions

Does ovulation happen on the same day every month?
No, even if your cycle length is consistent, ovulation day can vary by a few days. Stress, illness, travel, and other factors can affect ovulation timing.
When should I take an ovulation test?
Start testing 3-4 days before expected ovulation and test at same time daily. Positive result indicates ovulation will occur within 24-36 hours.
My cycle is irregular, how can I track ovulation?
Combination of basal temperature, cervical mucus tracking, and ovulation tests provides more reliable results. Use an app to record data.
Is ovulation pain (mittelschmerz) normal?
Yes, some women feel mild abdominal pain or twinges on one side during ovulation. This is normal and can indicate ovulation is occurring.
Can I get pregnant after ovulation?
The egg only survives 12-24 hours. Conception chance 24+ hours after ovulation is very low. Ideal is intercourse before or on ovulation day.
Does every cycle have ovulation?
No, anovulatory cycles (without ovulation) can occur. Stress, weight changes, PCOS can cause this. If cycles are very irregular, consult a doctor.
Does age affect ovulation?
Yes, after age 35 egg quality and quantity decreases, ovulation may become irregular. Anovulatory cycles are more common after age 40.

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