Money basics, with the math shown.
Plain-English guides to budgeting, saving, debt, credit and how interest works. Every guide shows the formula, walks through an example you can rerun, and links to official sources.
Guides
All articlesWhat Inflation Does to Your Savings (With a Calculator)
Inflation makes each dollar buy less over time. Learn the formula, see what $1,000 could buy in 10, 20 and 30 years, and how to think about your real return.
How Much Should You Keep in an Emergency Fund?
A practical guide to emergency savings: how to set a target, how to build it, where to keep it and when to use it, with a free calculator.
How Credit Scores Are Calculated: The 5 FICO Factors Explained
FICO credit scores are built from five categories: payment history, amounts owed, length of history, new credit and credit mix. See how much each matters and what you can do.
How Compound Interest Works (With a Free Calculator)
Compound interest means earning interest on your interest. Learn the formula, see worked examples with monthly contributions and try the calculator.
Debt Snowball vs. Debt Avalanche: Which Pays Off Debt Faster?
Compare the debt snowball and debt avalanche methods with a worked three-debt example, real payoff times and interest totals, plus a free payoff calculator.
APR vs. APY: What's the Difference and Why It Matters
APR is the stated yearly rate, while APY includes compounding. Learn the formula, see how compounding changes the result, and try the APR to APY calculator.
The 50/30/20 Budget Rule: How It Works and When It Doesn't Fit
Split your take-home pay into needs, wants and savings with the 50/30/20 rule. See a worked example, a calculator and when to adjust the percentages.
Who writes this
I'm Santiago Gonzalez, an electrical engineer. Engineers like to check the numbers, so that is how these guides are written. I'm not a licensed financial advisor: read About and the editorial policy to see how the content is made, and the disclaimer for what it is and is not.