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
In 30 years, you could have
$660,849
≈ $315,055 in today's money · about 71% of it is growth
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 CalculatorUnderstand how time, contributions, returns, and inflation shape long-term wealth.
- Retirement CalculatorEstimate your retirement balance and income from savings, contributions, returns, and inflation.
- Portfolio Allocation CalculatorSplit your money across assets and see your weighted return, concentration, and long-term growth after inflation.
- Portfolio Rebalancing CalculatorCompare your current mix against a target allocation and estimate what to buy or sell to rebalance.
- Inflation CalculatorTranslate future money into today's purchasing power and see what inflation quietly costs.
- Dollar Cost Averaging CalculatorCompare investing all at once with spreading the same amount over time.
- FIRE CalculatorEstimate how much you need and when financial independence becomes possible.
- Coast FIRE CalculatorSee when your current investments could grow to support independence without adding more.
- Safe Withdrawal Rate CalculatorExplore how different withdrawal rates affect how long a portfolio could last.
- Dividend Reinvestment CalculatorProject how reinvested dividends can compound into a growing income stream.
Straight answers to specific questions
One question per page, answered with a number under stated assumptions — and the calculator is already loaded, so you can swap in your own figures and watch the answer move.
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 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.
- How Compound Interest Works: A Beginner's Guide6 min readWhy 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.
- Why Inflation Matters5 min readWhy 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.
- How to Choose Your Portfolio Allocation7 min readHow 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.
- Is Dollar-Cost Averaging Right for You?7 min readHow 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.
- Lump Sum vs Dollar-Cost Averaging: How They Compare8 min readInvesting a lump sum all at once versus spreading the same amount over time: the trade-offs, a worked example, and what the evidence shows.
- ROI vs CAGR: What's the Difference?7 min readROI measures the total percentage gain; CAGR measures annualized growth. Why they differ, a worked example, and when each is the right lens.
- Total Return vs Price Return6 min readTotal return counts price change plus dividends reinvested; price return counts only price. How the two differ and when each is used.
- Real Return vs Nominal Return6 min readNominal return is the raw percentage earned; real return subtracts inflation to show the change in purchasing power. With the Fisher equation.
- CAGR vs Average Annual Return: Why They Differ7 min readAveraging yearly returns overstates real growth because of volatility drag. CAGR is the compounded rate that matches your ending balance.
- Dividend Yield vs Dividend Growth7 min readDividend yield is the income a stock pays now; dividend growth is how fast that payment rises. The tradeoff, and how reinvestment changes it.
- Asset Allocation vs Diversification7 min readAsset allocation is how you split money across asset classes; diversification is how widely you spread risk within them. How the two work together.
- Portfolio Allocation by Age: Rules of Thumb8 min readHow age-based rules of thumb — 60/40 and '100/110/120 minus age' — frame stock and bond splits. Explained as conventions, not recommendations.
- Index Fund vs ETF: What's the Difference?7 min readAn 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.
- Simple Interest vs Compound Interest: What's the Difference?7 min readSimple interest is calculated only on your original principal; compound interest is calculated on the principal plus the interest already earned, so it grows faster over time. A neutral, worked-example guide.
- CAGR vs IRR (and XIRR): What's the Difference?8 min readCAGR assumes one lump sum growing at a smooth annual rate; IRR (and its spreadsheet form XIRR) accounts for money added and withdrawn at different times. A neutral, worked-example guide to which return measure fits which situation.
- FIRE vs Coast FIRE: What's the Difference?7 min readFull FIRE means enough invested to live off withdrawals now; Coast FIRE means enough invested that growth alone reaches your number by retirement age, so you only cover today's expenses. A neutral, worked-example guide.
- Coast FIRE vs Barista FIRE: What's the Difference?7 min readCoast FIRE means your invested balance can grow to your retirement number on its own, so you only cover today's expenses. Barista FIRE means you semi-retire and cover part of your expenses with part-time income. A neutral, worked-example guide.
- 3.5% vs 4% Withdrawal Rate: How They Compare7 min readThe 4% rule and a more conservative 3.5% rate set how much you withdraw from a portfolio each year. See what a lower rate changes for income and resilience, under stated assumptions, with a neutral worked example.
Popular financial concepts
Short, jargon-free definitions of the ideas that drive long-term returns—compounding, inflation, real return, diversification, and more.
Start learning long-term investing
New to long-term investing? Start with the concepts that explain how time, inflation, risk, and portfolio choices affect financial outcomes—then put them together in a calculator.
- What is Compound Interest?Understand how compound interest lets your money grow on its own growth over time.
- What is Inflation?Understand how inflation raises prices over time and quietly reduces what your money can buy.
- What is Real Return?Understand how real return shows your growth in purchasing power after inflation.
- What is CAGR?Understand how CAGR measures the smoothed annual growth rate of an investment over time.
- What is Diversification?Understand how spreading investments across assets reduces the risk of any single one.
- What is Asset Allocation?Understand how dividing money across asset classes balances risk and return.
- Open Retirement CalculatorEstimate your retirement balance and income from savings, contributions, returns, and inflation.
These guides are educational only and are not personalized financial advice. Browse all learning guides.
Rionux provides educational tools and explanations only. It does not provide personalized financial advice. Read the full disclaimer.