Rent index

The rent index isolates housing from the wider cost-of-living number. It's the median asking rent for a one-bedroom apartment in a central neighborhood, indexed against NYC at 100. Two cities can have similar overall cost-of-living indices but very different rent indices — and rent is usually the line item that decides whether a salary is enough.

Why central neighborhoods? Because they're the most comparable across cities. Suburban or peripheral rents vary enormously by transit quality, school catchments, and city size. Central rent is closer to a like-for-like comparison.

Read the rent index alongside the cost-of-living index. When rent index is much higher than the cost-of-living index, housing is the dominant cost driver; you can save a lot by moving to a cheaper neighborhood or downsizing. When the two are close, the city's cost is spread more evenly and rent optimization gains less.