Money guides

Plain-English explainers on the ideas behind our calculators. Each guide covers what a concept means, why it matters, and how to put a real number on it.

Debt Avalanche vs Debt Snowball: Which Pays Off Faster?

Two proven payoff methods compared, and why the size of your monthly payment matters more than either one.

How the 4% Rule Actually Works

Where the famous retirement rule came from, the 25x shortcut, and the assumptions it quietly makes.

APR vs APY: The Difference That Costs You Money

Why the same interest rate can be quoted two ways, and how compounding makes card debt grow faster than the sticker rate.

What a 1% Investment Fee Really Costs Over 30 Years

A one percent fee sounds tiny. Over three decades it can quietly claim a six-figure share of your portfolio.

How Big Should Your Emergency Fund Be?

The 3-to-6-months guideline, who needs more, where to keep the money, and how to build it a month at a time.