What Is Cost of Living and How Is It Calculated?
Last updated: March 15, 2026
The Short Answer
Cost of living measures how much money you need to maintain a certain standard of living in a specific location. When someone says "the cost of living in San Francisco is 45% above the national average," they mean that a typical basket of goods and services (housing, food, transportation, healthcare, utilities) costs 45% more there than the national baseline.
The number itself is an index, usually set so that the national average equals 100. A city with an index of 85 is roughly 15% cheaper than average. A city at 120 is roughly 20% more expensive. Simple in theory, but the details matter.
Where the Numbers Come From
In the United States, the most authoritative cost of living data comes from the Bureau of Economic Analysis (BEA), which publishes Regional Price Parities (RPPs). These measure the price levels of goods, services, and rents across states and metropolitan areas relative to the national average. The BEA uses price data from the Bureau of Labor Statistics Consumer Price Index (CPI) program, which collects prices on thousands of items in hundreds of locations.
Other data sources that feed into cost of living analysis include the Census Bureau's American Community Survey (for median incomes, rents, and home prices), the Tax Foundation (for state and local tax rates), and the Department of Housing and Urban Development (for fair market rental data).
For international comparisons, the World Bank and OECD publish purchasing power parity (PPP) data that adjusts for price differences between countries. These are less granular than domestic data but provide useful country-level comparisons.
What the Categories Mean
Cost of living is not one number. It breaks down into categories, and the differences between categories often matter more than the overall figure.
Housing is almost always the largest factor and the most variable. It includes rent or mortgage costs, property taxes, and homeowner's insurance. Housing alone accounts for roughly 33% of the average American household budget, and the gap between the cheapest and most expensive US cities is enormous: housing in San Francisco costs over three times the national average, while housing in Mississippi costs roughly 63% of it.
Groceries vary less dramatically but still matter. Hawaii's groceries cost about 40% more than the mainland average because nearly everything is shipped across the Pacific. The Midwest tends to be slightly below average.
Transportation includes vehicle costs, gas, insurance, and public transit. Cities with good public transit (New York, Chicago) can actually reduce this category despite higher overall costs.
Healthcare varies by region and is influenced by local hospital systems, insurance markets, and provider availability. Healthcare costs are higher in the Northeast and lower in the South and rural areas, though quality also varies.
Utilities depend heavily on climate. Heating costs dominate in the Northeast and Midwest. Cooling costs dominate in the South and Southwest. States with cheap hydroelectric power (Washington, Oregon) have lower electricity costs.
What the Numbers Cannot Capture
Every cost of living index has blind spots. Taxes are often excluded or simplified. State income tax, local income tax, sales tax, and property tax rates vary enormously and can add thousands of dollars per year to your effective cost of living. A no-income-tax state like Washington or Texas looks different in the calculator when you add the 10%+ sales tax or 1.7% property tax rate.
Insurance costs, particularly homeowner's insurance in hurricane-prone states like Florida and Louisiana, can add $3,000 to $10,000 per year that standard indices do not fully capture.
Lifestyle choices are invisible to the data. Two people earning the same salary in the same city can have vastly different financial experiences based on whether they own or rent, have children, drive or take transit, cook at home or eat out.
And the biggest blind spot of all: quality. A cost of living index can tell you that healthcare in Mississippi costs 15% less than the national average, but it cannot tell you whether the healthcare system will meet your needs. Lower costs sometimes reflect lower quality, fewer options, or less competition.
How to Use This Data
The most useful way to think about cost of living is as a starting point, not a final answer. Use the category breakdown to identify where the biggest differences lie. Compare your actual spending patterns against the averages. Factor in taxes explicitly. And remember that the number is a regional average; the specific neighborhood, specific house, and specific grocery store you choose will matter more than the index.
That is exactly what our salary calculator is designed to help with. Enter your actual salary and two locations, and see the category-by-category breakdown rather than a single oversimplified number.