Regional price index

Ranked most expensive first. An index of 1.10 means the labour portion of an estimate is multiplied by 1.10 in that state; the material portion is not touched. A blank ZIP code gets 1.00, the national average.

Why only labour

This is the single biggest difference between the prices here and the prices on most other calculator sites, and it is worth arguing about rather than taking on trust.

A bag of concrete mix is a manufactured good on a pallet. It costs roughly the same in Mississippi as in New Jersey, because it is made and shipped by the same companies to the same big-box chains. What genuinely differs by geography is the hour of a person’s work. Multiplying an entire estimate by one “local cost factor” inflates the material half by a number that mostly reflects the price of housing.

So the material and the labour are computed separately, and only the labour carries this index. Heavy and bulk materials get a freight sensitivity of their own instead, because what moves the delivered price of stone or ready-mix is the distance to the pit or the plant — not the state line.

Where the index comes from, and what is wrong with it

It is the federal Regional Price Parities series, which measures what a fixed basket of goods and services costs in each state against a national average of 100. It is published annually, it is free, and it is methodologically solid for what it is designed to do.

It is still a proxy, and we would rather say so than imply more precision than we have. The all-items parity is heavily influenced by rent, which correlates with construction wages but is not the same thing. The direct measure would be state-level construction occupation wages from the federal occupational survey. Moving to it is recorded as pending in the changelog; until it happens, this is an approximation doing an honest job, and the page it feeds says so too.

Reading the spread

The whole range runs from about 87 to about 111, which is a spread of roughly a quarter between the cheapest and most expensive states. On the labour half of a small job that is real money but rarely decisive; on a large one it is the difference between two quotes. Within a state the variation between a city and a rural county is often larger than the variation between states — no state-level index can capture that, and a calculator that claims to is guessing.