Money guides
Short, plain-English explanations of the concepts behind our calculators. Every guide is reviewed for accuracy and dated so you know how fresh it is.
What Is Compound Interest? A Simple Guide
How compounding works, the formula, APR vs. APY, and five ways to make it work for you.
Read the guide →Mortgage Calculator With Taxes and Insurance
How your true monthly payment is calculated: PITI, escrow and a worked example.
Read the guide →Biweekly vs. Monthly Mortgage Payments
How much interest you really save by paying biweekly — with the math.
Read the guide →Refinance Break-Even: When Does Refinancing Pay Off?
The formula, closing-cost norms for 2026, and when not to refinance.
Read the guide →Refinance Closing Costs in 2026
What's normal, line by line — and how to lower them.
Read the guide →Debt Snowball vs. Debt Avalanche
Which payoff method saves you more? A worked three-card example, both ways.
Read the guide →The Minimum-Payment Trap
What happens if you only make minimum payments — the true cost in years and dollars.
Read the guide →The Power of Compound Interest
What $200 a month becomes in 30 years — and the cost of starting 10 years late.
Read the guide →Compound vs. Simple Interest
Formulas, examples and the key differences that matter for your money.
Read the guide →How Much Do You Need to Retire?
The 4% rule explained with real examples.
Read the guide →401(k) vs. Roth IRA in 2026
Which should you max out first? 2026 limits, verified from the IRS.
Read the guide →What Is a Good Annual Return?
Historical averages by asset class — stocks, bonds and cash.
Read the guide →How to Calculate CAGR
The formula every investor should know, with three worked examples.
Read the guide →2026 Federal Income Tax Brackets Explained
Real examples for single and joint filers, sourced from the IRS.
Read the guide →How Much Tax Is Taken Out of Your Paycheck?
State-by-state breakdown, no-income-tax states, and a CA vs. TX comparison.
Read the guide →How to Calculate ROI
Formula, examples, and five common mistakes to avoid.
Read the guide →ROI vs. ROAS vs. IRR
Which metric should you actually use — and when?
Read the guide →Profit Margin vs. Markup
What's the difference, and why mixing them up costs sellers money.
Read the guide →What Is a Good Profit Margin?
Benchmarks by industry for 2026, gross vs. net explained.
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