This page is the public description of how salary:converter computes cost of living, tax, neighborhood costs, and equivalent salaries. It uses product facts already published on About, llms.txt, and the live calculators. We do not invent sources or refresh dates here.
Coverage
Cost-of-living and salary pages cover 113 cities and 2,483 neighborhoods. Retirement planning is a larger set: 230 retire cities (visa, tax, and budget tools). Those two numbers are not interchangeable. Rankings that say “of 113” are COL/salary rankings, not retire rankings.
Cost of living index (COLI)
COLI is indexed to New York City = 100. A city with COLI 50 has living costs of about half of New York. A city with COLI 122 is about 22% more expensive than New York. Profession lifestyle-equivalent salaries scale the New York baseline by city COLI / 100, then convert to local currency with ECB reference rates.
That lifestyle equivalent is not market pay. Local-market pay is a separate number, badged the same way as Is my salary good?: Verified (national statistics), OECD / estimated, or COLI estimate only.
Tax model
Income tax is modelled as a single filer using progressive national brackets and mandatory social contributions embedded in the converter. We do not model married filing jointly, dependents, or itemized deductions. Figures are estimates.
Neighborhoods
Neighborhood costs are rent-index multipliers relative to the city average (1.00 = city-wide 1BR rent). A multiplier of 1.20 means about 20% above city-average rent; 0.80 means about 20% below. They are estimated from local rental indices and property data, not a separate full COL basket per neighborhood.
Last data refresh
The last recorded data timestamp in the published site index (llms.txt) is April 2026. City-page structured data uses datePublished / dateModified of 2026-04-02 where present. This methodology page was published 1 September 2026. We do not have a later recorded COL/salary refresh in the repo, so we do not stamp a newer data date.
Sources
As listed on About and llms.txt (not new sources):
- Cost of living — Numbeo Cost of Living Index; Expatistan is also cited on About.
- Salaries — U.S. Bureau of Labor Statistics (OES), Glassdoor, PayScale. Local-market badges on salary pages additionally use the same national-statistics / OECD wage-ratio set as /is-my-salary-good/ (BLS OES May 2024, ONS ASHE April 2024, OECD Earnings Database, and the other named offices on that page).
- Tax rates — OECD Taxing Wages and national tax authority brackets (single filer).
- Exchange rates — European Central Bank reference rates.
- Healthcare / safety / visas / climate (retire tools) — WHO Global Health Observatory, Numbeo, Global Peace Index, official immigration sites, Weatherbase / Climate-Data.org, as listed in llms.txt.
New York software engineer baseline
The canonical mid-career New York software engineer figure in the salary generators is $85,000 USD (salaryRanges['Software Engineer']['mid']). Lifestyle equivalents (for example London ≈ £56,005) are that baseline scaled by city COLI, not local market pay. We do not use a $120,000 figure as a market salary.
See also About, Is my salary good?, and llms.txt.