FinTools guides
Plain-language guides to common money questions: how compound interest works, APY versus APR, debt payoff strategies, retirement targets, employer matching, and the costs that eat returns. Each one pairs with a free browser calculator so you can read the why and then run your own numbers.
All guides
APY vs APR: What The Difference Costs You Learn the difference between APY and APR, why the same quoted number earns or costs more after compounding, and which figure to compare when shopping. Avalanche vs Snowball: Which Debt Payoff Method Is Faster? Compare the avalanche and snowball debt payoff methods, see a worked two-debt example, and learn when the difference between them is small. How Much Do You Need To Retire? The 4% Rule Explained Learn where the 4% rule and the 25x spending rule of thumb come from, what they ignore, and how to adjust a retirement target for other income. 401(k) Employer Match: How Not To Leave Free Money Behind Learn how common 401(k) employer match formulas work, what a match is worth over 30 years, and how vesting and debt priorities fit in. How Compound Interest Works (With Worked Examples) Learn how compound interest works with worked examples: compounding frequency, contribution timing, the Rule of 72, and compounding on debt. How Fees And Inflation Quietly Eat Investment Returns Compare investment fees over 10, 20, and 30 years with a chart and downloadable CSV, and learn how inflation changes the purchasing power of your returns.