How the Index Is Built
Researchers price a standardized "basket" of goods and services in each city — a two-bedroom apartment, a gallon of milk, a doctor's visit, a gallon of gas — then weight those categories by how much an average household actually spends on each one. Housing typically carries the heaviest weight since it's the largest expense for most people.
Equivalent Salary = Current Salary × (Destination Index ÷ Current Index)
A Worked Example
Say the national average index is 100. Austin, TX scores around 108, and San Francisco, CA scores around 180. Someone earning $75,000 in Austin wondering what salary they'd need to maintain the same lifestyle in San Francisco would calculate:
| City | Index | Salary |
|---|
| Austin, TX (current) | 108 | $75,000 |
| San Francisco, CA (target) | 180 | $75,000 × (180 ÷ 108) = $125,000 |
That $125,000 is the rough salary needed in San Francisco to have equivalent purchasing power to $75,000 in Austin — driven overwhelmingly by the housing gap between the two cities.
What Goes Into the Index
- Housing: rent or mortgage costs, usually the heaviest-weighted category
- Groceries: a standardized basket of common food items
- Utilities: electricity, gas, water, internet
- Transportation: gas prices, public transit fares, car insurance
- Healthcare: typical doctor visit and prescription costs
- Miscellaneous: restaurants, clothing, entertainment
Cost of Living Index vs. Inflation
These are often confused but measure different things. A cost of living index is a spatial comparison — how prices differ between places at the same moment in time. Inflation is a temporal comparison — how prices change over time in the same place. A city can have a high cost of living index (expensive relative to other cities) with low inflation (prices not rising quickly there right now), or vice versa.
Figures shown are illustrative examples only and not financial advice. Actual index values vary by data source and update over time; always check the publication date of any index you reference.
Frequently Asked Questions
What is a cost of living index in simple terms?
A cost of living index is a single number that shows how expensive a city is compared to a baseline, usually set at 100. A score of 130 means that city is roughly 30% more expensive than the baseline.
What is a good baseline for a cost of living index?
There's no universal baseline. Some indices use the U.S. national average as 100, others use a specific reference city like New York City. Always check which baseline a given index uses before comparing numbers across sources.
What categories go into a cost of living index?
Typical categories include housing (rent or mortgage), groceries, utilities, transportation, healthcare, and miscellaneous goods and services, usually weighted by how much an average household spends on each.
How do I use a cost of living index to compare salaries?
Divide the index of your destination city by the index of your current city, then multiply your current salary by that ratio to estimate the equivalent salary needed to maintain the same lifestyle.
Is a cost of living index the same as inflation?
No. A cost of living index compares prices between different locations at the same point in time. Inflation measures how prices change over time within the same location.
Are cost of living indices accurate for individuals?
They're a useful starting estimate but represent averages, not your personal spending pattern. A renter, a homeowner, and someone with no car will experience the same city very differently than the index average suggests.