Period-Calculator.net

**Period-Calculator.net** is a simple, privacy-focused tool to help users predict their next menstrual period, ovulation day, and fertile window. It only requires 3 inputs:

- Last period start date

- Period length (e.g. 5 days)

- Average cycle length (e.g. 28 days)

Once submitted, users see:

- Next predicted period dates

- Estimated ovulation day

- Fertile window

- A color-coded monthly calendar with:

- 🩸 pink background and heart icon for period days

- 👶 green background and baby face icon for ovulation day

Built with **Next.js and server-side rendering (SSR)** for SEO and speed. All calculations happen locally in the browser — we **never store or send any personal data**.

Optimized for global mobile users (90%+ mobile traffic), the site is lightweight, fast-loading, and respects user privacy by design.