Free Ovulation Calculator

Enter your cycle details to find your most fertile days this month. Know exactly when to try for the best chance of conception.

Calculate Your Fertile Window

We'll show you the 6 days each cycle when pregnancy is possible.1

Your Fertile Window

Estimated ovulation: —

Sun
Mon
Tue
Wed
Thu
Fri
Sat
Period
Fertile
Peak
Ovulation

Maximize Your Chances

Time intercourse 1-2 days before ovulation

The highest pregnancy rates occur when you have sex in the 2 days leading up to ovulation—not on ovulation day itself.1

Have sex every 1-2 days during fertile window

ASRM recommends intercourse every 1-2 days during your fertile window for optimal conception chances.1

Track ovulation for more accuracy

This calculator estimates based on averages. For precise timing, use ovulation predictor kits (OPKs) to detect your LH surge.

Track More Accurately

Calculators estimate based on averages. These tools confirm your actual fertile days.

As an Amazon Associate, we earn from qualifying purchases. This helps keep our tools free.

How does this calculator work?

Our ovulation calculator estimates your fertile window based on the calendar method. Here's the science behind it:

  • Ovulation typically occurs 14 days before your next period starts1
  • Sperm can survive in the reproductive tract for up to 5 days2
  • An egg lives only 12-24 hours after ovulation2
  • This creates a 6-day fertile window ending on ovulation day1

How accurate is this calculator?

Calendar-based predictions work best for women with regular cycles. However, even regular cycles can vary by a few days month to month.

For more precise tracking, consider combining this calculator with:

  • Ovulation predictor kits (OPKs) to detect your LH surge
  • Basal body temperature (BBT) tracking
  • Monitoring cervical mucus changes

If your cycles are irregular (varying by more than 7 days), consult a healthcare provider for personalized guidance.