COUNTY · IN
Hamilton County, Indiana
Hamilton County is a county in Indiana with FIPS code 18057 and an estimated population of 371,645 (Census 2023), 4th largest of 92 in the state.
County facts
- Name
- Hamilton County
- State
- Indiana
- Type
- county
- FIPS code
- 18057
- State FIPS
- 18
- Population (2023)
- 371,645
- Change since 2020
- +6.5%
- State rank
- 4 of 92
Population is the Census Bureau’s Vintage 2023 estimate.
Questions
What is the FIPS code for Hamilton County?
Hamilton County, Indiana has the five-digit FIPS code 18057: 18 for the state and 057 for the county.
What state is Hamilton County in?
Hamilton County is in Indiana.
How do I know if an address is in this county?
Use the address lookup. ZIP codes and city names can cross county lines, so an address is the reliable check.
Sources: U.S. Census Bureau geographic reference files; Census Bureau Population Estimates, Vintage 2023. Last reviewed 2026-10-27.