Guides
Plain-language explanations of the concepts behind the numbers, for when a calculator result raises a "wait, why?" General education, not financial advice.
Aug 10, 2026
How amortization actually works: why your early payments are mostly interest
A fixed-rate loan charges the same payment every period, but the interest-versus-principal split shifts dramatically over the loan's life. Here's why.
Aug 14, 2026
APR vs. interest rate: what's the actual difference
The interest rate prices the money you're borrowing. APR folds in certain fees and spreads them over the term. Here's what that means when comparing loan offers.
Aug 18, 2026
Principal, interest, taxes, insurance: what's actually in a mortgage payment (PITI)
A mortgage payment is rarely just principal and interest. Here's what PITI stands for, how escrow works, and why a P&I-only estimate can understate your real payment.
Sep 24, 2026
15-year vs. 30-year mortgage: what the lower payment really costs
A 30-year mortgage has a lower payment; a 15-year mortgage can save six figures in interest. A worked comparison, plus the case for each.
Sep 24, 2026
How much house can I afford? The 28/36 rule explained
How lenders use debt-to-income ratios to size your mortgage, a worked example on a $90,000 income, and what the ratios leave out.
Sep 24, 2026
When does refinancing make sense? Break-even points and the reset-the-clock trap
How to calculate the break-even point on a refinance, why a lower payment can still cost more over the life of the loan, and when refinancing tends to pay off.
Sep 24, 2026
How long should a car loan be? 36 to 84 months compared
Longer car loans lower the payment but raise the total cost and the risk of negative equity. The numbers for every common term, and how to choose.
Sep 24, 2026
How credit card interest works, and why minimum payments take so long
Daily periodic rates, grace periods, and minimum payment math, with a worked example showing how a fixed payment cuts years off a credit card balance.