Guides

Understand the numbers behind our calculators — cost of living, pay, taxes and mortgages, explained simply.

• Cost of Living Explained: What It Means & How It's MeasuredWhat 'cost of living' actually measures, how BEA Regional Price Parities work, why government data lags, and how to compare cities fairly using real numbers.
• Understanding Your Take-Home PayHow gross salary becomes net pay after federal tax, FICA and state tax — with 2024 IRS brackets, real examples, and why the same salary nets more in some states.
• How Much House Can You Afford?The debt-to-income rule lenders use, what PITI includes, the 28/36 rule, PMI, and how to find a realistic home price for your income using real 2024 rates.
• What Salary Do You Need to Live Comfortably?A budgeting framework (50/30/20) plus real local rent, groceries, and utilities to estimate the salary a city actually requires — with worked examples.
• How Mortgage Payments Work (Amortization Explained)Why early payments are mostly interest, how the monthly amount is calculated, and how rate and term change your total cost — with a real $300,000 example.
• Should You Take a Higher Salary in a Pricier City?How to compare a $95k offer in Austin vs $120k in NYC using real cost-of-living data, take-home math, and the 30% affordability rule.
• Rent vs Buy: Which Makes Sense at Today's Rates?The real math of renting vs buying with 7% mortgage rates, real home values, and hidden costs — not the oversimplified 'renting is throwing money away' take.
• Which No-Income-Tax State Actually Saves You Money?Nine states have no income tax — but higher property or sales taxes can eat the savings. Here's the real math for each.
• Is Moving to a Cheaper City Worth the Pay Cut?How to decide if a lower salary in a cheaper city actually improves your standard of living — using RPP, real rent, and take-home math.
• Should You Refinance Your Mortgage?The break-even math for refinancing at today's rates — when it saves money, when it doesn't, and the costs most people forget.
• Should You Pay Off Debt or Invest the Extra Money?The real math of paying off debt vs investing — when 7% loan interest beats the stock market, and when it doesn't.
• 15-Year vs 30-Year Mortgage: Which Is Right for You?The real tradeoff between a 15-year and 30-year mortgage — $700/month difference, $233,000 in interest savings, and what you give up for it.
• How the Standard Deduction Changes Your Effective Tax RateThe 2024 standard deduction ($14,600 single, $29,200 married) and how it lowers your effective tax rate — with worked examples at three income levels.
• PMI: When It Applies and How to Remove ItPrivate mortgage insurance costs 0.3–1.5% of the loan annually when you put down less than 20%. Here's when it starts, when it ends, and how to remove it early.
• How Compound Interest Grows Your SavingsThe real math of compound interest — why $10,000 at 5% becomes $16,471 in 10 years, and how starting early beats saving more later.
• State Tax Reciprocity: Working Across State LinesIf you live in one state and work in another, reciprocity agreements can save you from filing two state tax returns. Here's which states have them and how it works.
• FICA Explained: Social Security and Medicare TaxesThe 7.65% payroll tax everyone pays — 6.2% Social Security up to $168,600, 1.45% Medicare on everything. How it works, the wage cap, and the self-employed double hit.
• How BEA Regional Price Parities Are CalculatedThe methodology behind the RPP index — what's in the basket, how BEA collects prices, and why state RPP differs from metro RPP.
• Why ACS Rent Data Lags Reality by 18 MonthsThe Census ACS 5-year estimates that power our rent data take 18 months to publish. Here's why, what that means, and why we still use them.
• What Our 4-Metric Completeness Gate Excludes and WhyWe noindex cities missing any of 4 required metrics. Here's what the gate is, what it excludes, and why a smaller, complete index beats a larger, gappy one.