Investing basics, without the jargon.
Compound interest, index funds, asset allocation, and the boring strategy that wins
North-star rule of thumb
$200/mo at 7% for 30 years ≈ $244,000
$72K of contributions, $172K of growth. Compounding does most of the work — your job is to keep the contributions coming.
The overview
Investing is — almost embarrassingly — a solved problem for most people. Set a target-date fund or a three-fund portfolio of low-cost index funds. Contribute every month. Don't sell during scary years. Wait decades. That's it. Everything that sounds more sophisticated than that has, on average across long time periods and across millions of investors, underperformed it.
The Investment Projection and Savings vs Investing calculators below show why: compound interest is the cheat code, and a 1% fee difference over 30 years is tens of thousands of dollars. The boring approach wins because it's cheap (fees compound the wrong way), it's diversified (no single bad bet ruins it), and it's automated (you don't have to remember to do it).
Below: compound interest in plain English, index funds vs ETFs vs mutual funds, dollar-cost averaging vs lump-sum, asset allocation by age, Roth vs Traditional accounts, the safe withdrawal rate, and the historical S&P 500 returns nobody can quite agree on.
What we don't do: pick stocks, time the market, or tell you what 'this market' calls for. The plainest, most-evidence-based advice in personal finance is also the least exciting, and that's the point.
Run the math
The calculators that ground this hub. Free, sourced defaults, your inputs never leave your browser.
Learn the basics
Bite-sized lessons with quizzes and XP. Two minutes a day.
Deeper reads in this guide
Each one is a focused, plain-English breakdown. Articles markedComing soonwill publish on the moneyscale.app weekly content rhythm.
Compound interest, in plain English
The cheat code, the formula, and the visual that makes it click.
Index funds vs ETFs
Same idea, slightly different mechanics — and when each one wins.
Dollar-cost averaging (DCA)
The argument for boring, automated buying — and when lump-sum beats it.
Roth vs Traditional IRA
The bracket rule that decides for you in 90% of cases.
Asset allocation by age
Coming soonStocks/bonds split, target-date fund math, and the rule of thumb.
S&P 500 historical returns
Coming soonWhat '10% per year' actually looks like across real decades.
Safe withdrawal rate, beyond the 4% rule
Coming soonWhere the rule came from, when it's optimistic, when it's conservative.
How to start investing with $100
Three brokerages, two fund types, one boring plan.
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Not financial advice
Money Scale provides educational information about personal finance. For decisions that affect your money in a material way, consult a licensed professional you've personally vetted. See our affiliate disclosure for how we keep this site free.