Rionux is a growing set of free investing calculators built around one idea: don't just give you a number, help you understand it. Each tool shows the reasoning behind the result with clear charts and plain-language insights, in today's money and based on your own assumptions. Made for long-term investors, no signup, no advice — just clarity.
Hey everyone 👋
I kept hitting the same thing with finance calculators online — you punch in some numbers, get a big total, and that's it. No sense of why the number is what it is, or what actually moves it.
So I made Rionux. It's a growing collection of investing calculators, but the point isn't really the math — it's understanding it. Each one walks through what's happening behind the result and shows it in today's money, based on your own assumptions, so it feels honest rather than a shiny projection. It's free, runs in your browser, no account, and it's meant to teach — not to give advice.
It's still early and I'm adding to it, so I'd genuinely value your honest take — what's clear, what isn't, and what you'd want to see next. Thanks for taking a look
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Really like how the calculators show their work instead of just spitting out a number, the inflation-adjusted view is genuinely useful for sanity-checking my retirement assumptions.
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Maker
@arasyaka31982 Thanks, Aras "Show their work" is exactly the bar, a number you can't see the reasoning behind is hard to trust. The inflation adjusted view is there so you're sanity checking your retirement assumptions in today's money, not a nominal figure that looks bigger than it really is.
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The plain-language insights alongside the numbers genuinely helped me wrap my head around compounding over time. No signup friction made it easy to poke around and adjust assumptions without committing to anything.
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Maker
@lknurka6a Thank you, İlknur 🙏 Compounding sounds simple but only really clicks when you watch it play out, so glad the insights helped. And yep, no signup on purpose, freely changing the assumptions is where the "aha" happens.
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Tried the DCA calculator and the breakdown of why your average cost ends up where it does was genuinely helpful, not just a number on a screen. Love that there's no signup wall blocking the useful stuff.
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Maker
@meryemdemi73015 Thanks, Meryem 🙏 "Dollar-cost averaging" gets said a lot but rarely shown, glad the breakdown of how the average cost lands made it click, not just spit a number. And yep, no signup wall on the useful stuff, ever.
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The plain-language breakdowns next to each chart are genuinely well done - feels like having a patient friend walk you through the math instead of just spitting a number back at you.
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Maker
@ruzgar1320 Thank you, Rüzgar "A patient friend walking you through the math" is exactly the goal. Really appreciate you taking a look.
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Really like how the calculators show their work instead of just spitting out a number, the inflation-adjusted view is genuinely useful for sanity-checking my retirement assumptions.
@arasyaka31982 Thanks, Aras "Show their work" is exactly the bar, a number you can't see the reasoning behind is hard to trust. The inflation adjusted view is there so you're sanity checking your retirement assumptions in today's money, not a nominal figure that looks bigger than it really is.
The plain-language insights alongside the numbers genuinely helped me wrap my head around compounding over time. No signup friction made it easy to poke around and adjust assumptions without committing to anything.
@lknurka6a Thank you, İlknur 🙏 Compounding sounds simple but only really clicks when you watch it play out, so glad the insights helped. And yep, no signup on purpose, freely changing the assumptions is where the "aha" happens.
Tried the DCA calculator and the breakdown of why your average cost ends up where it does was genuinely helpful, not just a number on a screen. Love that there's no signup wall blocking the useful stuff.
@meryemdemi73015 Thanks, Meryem 🙏 "Dollar-cost averaging" gets said a lot but rarely shown, glad the breakdown of how the average cost lands made it click, not just spit a number. And yep, no signup wall on the useful stuff, ever.
The plain-language breakdowns next to each chart are genuinely well done - feels like having a patient friend walk you through the math instead of just spitting a number back at you.
@ruzgar1320 Thank you, Rüzgar "A patient friend walking you through the math" is exactly the goal. Really appreciate you taking a look.