About
Hi, I'm Gianni.
I built the calculators I wished existed.
I'm a software engineer from Haaltert, Belgium, and I've been investing my own money since 2020. Investment Calculator is where those two meet: free tools with honest math and clear explanations, so you can see what your money could do before you decide.
Good financial math shouldn't be hard to find, or hard to understand.
My missionClear financial math, free for everyone.
The road to Investment Calculator
2020My first investments
I started investing my own money and soon wanted to understand what my choices would mean over the long run.
Looking for a tool I could trust
The calculators I found were too simple, vague about their formulas or light on explanation. None combined accurate math with content that helped me understand the result.
Building it myself
As a software engineer, I did what felt natural: I built the tools I was missing and checked every formula against standard financial mathematics.
2025Launch
Investment Calculator went live in English in September 2025, followed a month later by Dutch, French and German versions.
Today
More than 20 free calculators and guides, backed by regularly refreshed historical data on stocks, inflation, precious metals and crypto.
What drives Investment Calculator
Accurate
Formulas follow standard financial mathematics, the same methods used in textbooks and professional tools.
Transparent
Every data source, update schedule and method is documented in the Data Guide.
Free for everyone
Every calculator works without an account. Signing in is only needed to save favorites.
Your language
Every page exists in English, Dutch, French and German, written in each language rather than translated word for word.
What makes it different?
This site is for anyone who wants to understand their numbers, not only for finance professionals.
Built by an investor
I invest my own money too, so I build the tools I want to rely on myself.
Real historical data
Market-based pages use real index returns, inflation figures and prices, not only assumed averages.
Explanations next to the numbers
Every calculator explains its formula, and the guides work through examples step by step.
Insight, not advice
The content is factual and educational. It shows what the numbers mean and leaves the decision to you.
Want the details? The Data Guide lists every data source, update schedule and methodology used on the site.
A question, an idea, or a number that looks wrong?
Send me an email at info@investment-calculator.net. I read every message and usually reply within 3 business days. Spotted an error in a calculator or guide? Tell me and I'll fix it. You can also find me on LinkedIn.