Ovulation Calculator
Predict your most fertile window from last menstrual period (LMP) and average cycle length. Shows ovulation date, fertile window (5 days before + ovulation day), next period date, and 6-cycle forecast.
What powers the Ovulation Calculator
Ovulation date prediction (cycle length - 14 days)
Fertile window (5 days before + ovulation)
Next period prediction
Due date if conception this cycle
6-cycle forecast for ongoing planning
Why the Ovulation Calculator is different
Browser-native
The Ovulation Calculator runs entirely in your browser. Input is processed locally — never uploaded, never logged, never cached anywhere outside your device.
No artificial limits
No daily quotas, no character ceilings, no "upgrade for more" walls. Every feature is the complete feature — the same on the first use as the thousandth.
Production-grade quality
Built to the same engineering bar as paid SaaS tools — accurate algorithms, audited logic, responsive design and accessibility-tested interactions.
Common use contexts
- Trying to conceive — timing intercourse for highest pregnancy chance
- Tracking cycle for general health awareness
- Planning around period dates for travel / events
- Sharing fertility window with partner
Private and secure
Zero upload
All processing happens in your browser. Input is never transmitted, logged or cached.
Works offline
Once the page loads, the tool runs without an internet connection. No network calls happen during use.
No tracking
No accounts, no cookies for tool state. Only aggregate analytics count visits at the page level.