Money guides
Updated July 2026
Short, plain-English explanations of the ideas behind our calculators. No jargon, no upsell — just the math and the reasoning so you can make your own decisions with confidence.
Guide
How compound interest really works
Compound vs simple interest, the formula, and worked examples showing $10,000 grow at 7%.
GuideDebt snowball vs avalanche
Which payoff method saves the most interest — and which keeps you motivated to finish.
GuideWhat is the FIRE movement?
The 25x rule, the 4% safe-withdrawal rate, and an honest look at the risks.