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Rionux
Investing with clarity

Rionux

Investing tools and education for long-term investors

Rionux helps long-term investors understand financial decisions through interactive calculators, practical educational guides, and clear glossary explanations.

Audience
Long-term investors
Focus
ETFs, Bitcoin, FIRE
Promise
Understanding, not hype
Try it liveCompound Interest
$
1-60
%

In 30 years, you could have

$660,849

≈ $315,055 in today's money · about 71% of it is growth

Open the full calculator

Calculators

Free investing calculators

Model compound growth, retirement, portfolio allocation, inflation, and more. Every calculator explains the assumptions behind the result—so you understand why the numbers move.

Compound Interest Calculator

Understand how time, contributions, returns, and inflation shape long-term wealth.

Retirement Calculator

Estimate your retirement balance and income from savings, contributions, returns, and inflation.

Portfolio Allocation Calculator

Split your money across assets and see your weighted return, concentration, and long-term growth after inflation.

Portfolio Rebalancing Calculator

Compare your current mix against a target allocation and estimate what to buy or sell to rebalance.

Inflation Calculator

Translate future money into today's purchasing power and see what inflation quietly costs.

Dollar Cost Averaging Calculator

Compare investing all at once with spreading the same amount over time.

FIRE Calculator

Estimate how much you need and when financial independence becomes possible.

Coast FIRE Calculator

See when your current investments could grow to support independence without adding more.

Safe Withdrawal Rate Calculator

Explore how different withdrawal rates affect how long a portfolio could last.

Dividend Reinvestment Calculator

Project how reinvested dividends can compound into a growing income stream.

View all calculators

Why Rionux

Understand your money with confidence.

Rionux combines free financial calculators with practical education so you can explore long-term investing, retirement planning, and wealth-building concepts through interactive tools—not speculation.

Interactive calculators

Explore compound interest, FIRE, portfolio allocation, inflation, and other financial concepts with fast, easy-to-use calculators.

Learn while you calculate

Every calculator is paired with educational articles and explanations so you understand the numbers instead of simply accepting them.

Transparent assumptions

Calculations are based on clearly explained formulas and assumptions. No hidden logic or black-box results.

Built for long-term investing

Rionux focuses on principles like compounding, diversification, inflation, and disciplined investing—not market predictions or speculation.

Always free

All calculators and educational resources are available without registration or subscription.

Growing knowledge library

New calculators, educational guides, glossary entries, and investing tools are added continuously to help you keep learning.

Learn

Learn the concepts behind the numbers

Plain-English guides connect each idea to the calculators, so you can see what changed and why. No jargon, no hype—just the reasoning behind long-term investing.

Read all guides
6 min read

How Compound Interest Works: A Beginner's Guide

Why time matters more than the return rate, and how to put consistent long-term investing to work in your favour — with scenarios you can run yourself.

5 min read

Why Inflation Matters

Why long-term investors judge returns after inflation, what that does to a plan built on nominal numbers, and how to think about staying ahead of it.

7 min read

How to Choose Your Portfolio Allocation

How to decide the mix of stocks, bonds, and cash that fits your time horizon and tolerance for risk — with the trade-offs behind each choice.

7 min read

Is Dollar-Cost Averaging Right for You?

How to judge whether investing a fixed amount on a schedule suits your situation — where it helps, where it falls short, and the trade-offs to weigh.

8 min read

Lump Sum vs Dollar-Cost Averaging: How They Compare

Investing a lump sum all at once versus spreading the same amount over time: the trade-offs, a worked example, and what the evidence shows.

7 min read

ROI vs CAGR: What's the Difference?

ROI measures the total percentage gain; CAGR measures annualized growth. Why they differ, a worked example, and when each is the right lens.

6 min read

Total Return vs Price Return

Total return counts price change plus dividends reinvested; price return counts only price. How the two differ and when each is used.

6 min read

Real Return vs Nominal Return

Nominal return is the raw percentage earned; real return subtracts inflation to show the change in purchasing power. With the Fisher equation.

7 min read

CAGR vs Average Annual Return: Why They Differ

Averaging yearly returns overstates real growth because of volatility drag. CAGR is the compounded rate that matches your ending balance.

7 min read

Dividend Yield vs Dividend Growth

Dividend yield is the income a stock pays now; dividend growth is how fast that payment rises. The tradeoff, and how reinvestment changes it.

7 min read

Asset Allocation vs Diversification

Asset allocation is how you split money across asset classes; diversification is how widely you spread risk within them. How the two work together.

8 min read

Portfolio Allocation by Age: Rules of Thumb

How age-based rules of thumb — 60/40 and '100/110/120 minus age' — frame stock and bond splits. Explained as conventions, not recommendations.

7 min read

Index Fund vs ETF: What's the Difference?

An index fund is a strategy that tracks an index; an ETF is a structure that trades like a stock. How they relate and where they genuinely differ.

Glossary

Popular financial concepts

Short, jargon-free definitions of the ideas that drive long-term returns—compounding, inflation, real return, diversification, and more.

View all glossary terms

Rionux provides educational tools and explanations only. It does not provide personalized financial advice. Read the full disclaimer.