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Ovulation Calculator

Health & Fitness · Free · Runs entirely in your browser

Enter your last period date and cycle length — instantly find your most fertile days and next expected period.

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Details
Result
Estimated ovulation date
Fertile window (highest chance)
Next expected period
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How to use — Ovulation Calculator

  1. Enter the first day of your last period and set the average cycle length.
  2. Get your ovulation date, fertile window (when conception chances are highest), and next period instantly.

FAQ

What is ovulation?

The release of a matured egg from the ovary — this typically happens 14 days before the next period. The 5-6 days around this are best for conceiving.

What is the fertile window?

From 5 days before ovulation to the day of ovulation — sperm can survive up to 5 days, so this entire window is considered fertile.

Can this be used with irregular cycles?

The estimate is less accurate with irregular cycles. Basal body temperature or ovulation kits are more reliable — this tool is a starting point.

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