Ovulation Date Calculator
Work backward from your next expected period to find ovulation and your fertile window
Enter the date your next period is due and this calculator works backward 14 days to estimate your ovulation date, then shows the fertile window when conception is most likely (5 days before ovulation through 1 day after). It's handy if you're trying to conceive or simply want to know where you are in your cycle. Every date you enter is calculated right in your browser and never sent to a server.
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🔒 Everything runs 100% in your browser. Your files and input are never uploaded to any server.
How to use
- Pick the date your next period is expected to start in the date field.
- Your estimated ovulation date appears on screen automatically.
- Check the fertile window shown below it, running from 5 days before ovulation through 1 day after.
- If your cycle shifts, just pick a new date and everything recalculates instantly.
FAQ
- How is the ovulation date calculated?
- It uses the standard luteal-phase method: subtracting 14 days from the first day of your next expected period.
- Can I use this as a birth control method?
- No. Ovulation timing shifts with hormones, stress, and overall health, so it isn't a reliable way to prevent pregnancy.
- Are the dates I enter stored anywhere?
- No. Everything is calculated inside your browser, and the dates you enter are never transmitted or saved to a server.