Easy Ovulation Calculator — Find Your Most Fertile Days

Calculate your ovulation date and 5-day fertile window using your last period and average cycle length. Fast, private, and mobile-friendly.

Ovulation Calculator

How it works

Our ovulation calculator uses your last menstrual period (LMP) and average cycle length to estimate when you ovulate. Ovulation typically occurs about 14 days before your next period, so we calculate: ovulation date = LMP + (cycle length - 14 days). The fertile window includes the 5 days leading up to ovulation when pregnancy is most likely.

About This Ovulation Calculator

Use this Easy Ovulation Calculator to estimate the day you ovulate and the 5-day fertile window surrounding it. Ovulation is when an ovary releases a mature egg—this is the single best time for conception. Most cycles ovulate about 14 days before the next period, but individual cycles vary. Enter your last menstrual period (LMP) and average cycle length to get an instant, personalized result.

Why this matters: sperm can survive up to 5 days in the reproductive tract and the egg survives ~12–24 hours, so timing intercourse during the fertile window increases the chance of pregnancy. This tool is intended for general guidance—not medical diagnosis. If your cycles are irregular, consider tracking cervical mucus, basal body temperature (BBT) or using an ovulation test kit for better accuracy.

Use our related tools (Due Date Calculator, Conception Date Calculator) to plan next steps once you've found your fertile days.

Frequently Asked Questions

What is ovulation?

Ovulation is the process where an ovary releases a mature egg, which then travels down the fallopian tube where it can be fertilized by sperm. This typically occurs once per menstrual cycle, about 14 days before the start of the next period.

How accurate is this calculator?

This calculator provides estimates based on standard calculations and assumptions about regular cycles. For more accurate tracking, especially with irregular cycles, consider using ovulation predictor kits, tracking basal body temperature, or consulting with a healthcare provider.

Can I get pregnant before ovulation?

Yes, it's possible to get pregnant in the days leading up to ovulation. Sperm can survive in the female reproductive tract for up to 5 days, so intercourse during the fertile window (the 5 days before ovulation) can result in pregnancy.