I built a Rule #1 calculator to help investors find great businesses at fair prices

Hey everyone,

I got tired of jumping between different research tools just to answer one basic question:

“Is this a great business trading at a fair price?”

So I built a simple platform based on the Rule #1 investing methodology. The goal is to put the key information in one place and make the first assessment faster.

The app compares the current market price with its sticker price, which is calculated from historical EPS growth. Then it shows you other tools like:

1. The big 5 numbers (ROIC, Sales growth, EPS growth, Equity growth, Cash flow growth)
2. Moat and management notes
3. Indicators to see whether the market seems to be buying or selling
4. Group analysis, so you can run the same process across lists like the S&P 500

Everything in one place and shown in a visual, easy-to-understand interface.

The app is open source and public. I don’t make money from it; it’s just the tool I personally use for research, and I wanted to share it with others who invest in a similar way. There isn’t even a login, data is stored locally on your browser, for example when you save a business to your watchlist.

I’m open to feedback on how to improve the app.

This is not financial advice, and the app can have errors. Treat it as a research tool for finding businesses that may be worth analyzing further.

Live app:
[https://rule1calculator.com/](https://rule1calculator.com/)

GitHub repo:
[https://github.com/DiciMinuti/Rule-1-Investing-Calculator](https://github.com/DiciMinuti/Rule-1-Investing-Calculator)