Fertile window estimator
Fertile window = 5 days before ovulation through 1 day after (6 days total).
- Ovulation day
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- Window opens
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- Window closes
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- Peak fertility (3 days before ov.)
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About this tool
Fertile window estimator is a single-purpose utility on instant.tw, a free toolbox of calculators, converters, generators, and quick lookups. Everything works in your browser — nothing is uploaded, nothing is stored on a server unless explicitly noted.
Category: Health & Fitness. Browse more Health & Fitness tools.