Calculate Your Fertile Days

First day of last menstrual period:

Average menstrual cycle length:

Luteal phase length (optional): Days between ovulation and next period

Your Fertility Window

Next Period Start:

Ovulation Date:

Fertile Window:

Next Cycle Days:

Menstrual Cycle Chart

Menstruation

Follicular Phase

Ovulation

Luteal Phase

Important Note

This calculator provides estimates based on average cycle patterns. Individual variations can occur. For conception, the most fertile days are the 3 days leading up to and including ovulation. Track your basal body temperature and cervical mucus for more accurate predictions.

Understanding Your Ovulation Cycle

Ovulation is when a mature egg is released from the ovary, ready to be fertilized. This typically occurs about 14 days before your next period starts. Knowing when you ovulate can help you plan or prevent pregnancy.

How the Calculator Works

The calculator estimates your ovulation date by:

Counting forward from your last period start date
Subtracting the luteal phase length (typically 14 days) from your total cycle length
Identifying your fertile window (the 5-6 days leading up to ovulation)

Phases of Your Menstrual Cycle

Menstruation (Days 1-5): Shedding of the uterine lining
Follicular Phase (Days 6-13): Follicles in ovaries mature
Ovulation (Day 14 in 28-day cycle): Egg is released
Luteal Phase (Days 15-28): Uterus prepares for possible pregnancy

Signs of Ovulation

Slight rise in basal body temperature (0.5-1°F)
Change in cervical mucus (becomes clear and stretchy)
Mild pelvic or abdominal pain (mittelschmerz)
Increased sex drive
Breast tenderness

Frequently Asked Questions

This calculator provides estimates based on statistical averages. For women with regular cycles, it can predict ovulation with reasonable accuracy. However, stress, illness, travel, and other factors can affect your cycle. For best results, combine calculator predictions with tracking physical signs like basal body temperature and cervical mucus.

While pregnancy is most likely during the 5-6 day fertile window, it's possible (though less likely) to conceive outside this time. Sperm can survive in the female reproductive tract for up to 5 days, and ovulation timing can vary. If avoiding pregnancy, use protection throughout your cycle.

With irregular cycles, ovulation calculators are less reliable. You may want to track ovulation signs like basal body temperature, cervical mucus changes, or use ovulation predictor kits. The luteal phase (after ovulation) is typically more consistent (12-16 days), so tracking this can help predict future cycles.

To maximize conception chances:

Have intercourse every 1-2 days during your fertile window
Track ovulation with multiple methods (calculator, temperature, mucus)
Maintain a healthy weight and lifestyle
Reduce stress and get adequate sleep
Avoid smoking and limit alcohol
Consider preconception vitamins (especially folic acid)

Ovulation Calculator