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Ovulation Calculator
ヘルスEstimate your fertile window and next ovulation dates.
ttb run ovulation-calculator
28 days
Select dates to calculate fertile window
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Ovulation Calculator の使い方
Enter the first day of your last period and your average cycle length. The calculator estimates your ovulation date and fertile window (the 5 days before ovulation plus ovulation day). All data is processed locally and never sent to any server. Color-coded calendar view makes tracking easy.
1
Enter your parameters
Configure the inputs for the Ovulation Calculator according to your specific needs.
2
View real-time results
The utility instantly processes your request and displays the calculated outputs directly in your browser.
3
Copy or Download
Click the copy icon next to the final output to instantly grab the result, or export it if applicable.
よくある質問
When does ovulation occur?+
Ovulation typically occurs 12-16 days before the start of your next period (not 14 days after your last period). For a 28-day cycle, that's around day 14. For a 32-day cycle, it would be around day 18.
How long is the fertile window?+
Sperm can survive up to 5 days in the reproductive tract, and an egg lives for 12-24 hours after release. This creates a fertile window of approximately 6 days: the 5 days before ovulation through the day of ovulation.