County outline
Where Napa County is located
Area breakdown
Land accounts for 94.9% of Napa County’s measured area and water for 5.1%. Its combined area converts to 2,052.1 square kilometers or approximately 507,073 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 751.976 | 1,947.609 | 481,264.6 |
| Water | 40.326 | 104.444 | 25,808.6 |
| Total | 792.302 | 2,052.053 | 507,073.3 |
How Napa County compares
By original Census land area, Napa County ranks #48 of 58 in California and #1172 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 0.49 times the California county-equivalent median of 1,535.7 square miles. It accounts for 0.5% of the combined county land area in the state.
See the complete California ranking · What counts as a county equivalent?
Population and density of Napa County
The Census Bureau estimates that 132,949 people lived in Napa County on July 1, 2025. That ranks #502 of 3,222 county equivalents nationally and #34 of 58 in California. Since the April 1, 2020 estimates base of 138,023, the population has declined by 5,074 (−3.7%), compared with −0.5% for California as a whole.
With 752 square miles of land, that is 177 people per square mile (68 per km²), placing Napa County #686 nationally for density and #20 in California. The median county equivalent has 47 people per square mile; the California median is 112. Put another way, there are about 3.6 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 137,481 | 136,266 | 134,499 | 133,628 | 133,115 | 132,949 |
| Change | — | −1,215 | −1,767 | −871 | −513 | −166 |
U.S. Census Bureau, Vintage 2025 population estimates. Estimates are revised each year and are not decennial census counts. Density divides the whole population by the whole county’s land area, so it describes an average, not how settlement is distributed within the county. Population sources and methods.
Cities and towns in Napa County
5 incorporated places lie at least partly in Napa County. Together they are home to 112,681 people (84.8%); the other 20,268 (15.2%) live outside any incorporated place, in unincorporated communities and rural areas.
The largest is Napa city, with 76,562 residents in the county. Among places with at least 1,000 residents in 2020, American Canyon city grew fastest since then (+4.3%).
| Incorporated place | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Napa cityCounty seat | 76,562 | −3.5% | 18.1 |
| American Canyon city | 22,773 | +4.3% | 6.08 |
| St. Helena city | 5,194 | −4.3% | 4.961 |
| Calistoga city | 4,954 | −5.3% | 2.579 |
| Yountville city | 3,198 | −6.6% | 1.49 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Napa County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.
Metropolitan area
Napa County is a central county of the Napa, CA Metropolitan Statistical Area. Napa County is the area’s only county equivalent, so the metro area has the same 752 square miles of land. By combined land it ranks #313 of 393 metropolitan areas, and #317 by population. It belongs to the San Jose-San Francisco-Oakland, CA Combined Statistical Area.
ZIP codes
13 ZIP Code Tabulation Areas have land in Napa County; 10 of them have most of their land inside the county, and the others mainly cover neighboring areas.
94503945089451594558945599456294567945739457494576945919459995476
ZIP Code Tabulation Areas are the Census Bureau’s approximations of USPS ZIP Code service areas, from the 2020 Census relationship files. Lighter codes have less than half of their land in this county. Post-office-box and single-address ZIP Codes have no tabulation area.
Counties bordering Napa County
Napa County shares a land border with 4 county equivalents. Each of them has more land than Napa County. The largest neighbor is Sonoma County (1,575.3 mi²) and the smallest is Solano County (821.7 mi²). Together with its neighbors, Napa County forms a block of 5,417.2 mi² of land, of which it holds 13.9%.
| Bordering county equivalent | Land mi² | Size vs. Napa | Compare |
|---|---|---|---|
| Sonoma County | 1,575.3 | 2.1× larger | Compare |
| Lake County | 1,255.1 | 1.7× larger | Compare |
| Yolo County | 1,013 | 1.3× larger | Compare |
| Solano County | 821.7 | 1.1× larger | Compare |
How big is Napa County compared with U.S. states?
Napa County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.4 times as much. California’s county land could hold about 207 areas the size of Napa County.
Another way to picture it: the same land area would fill a square about 27.4 miles (44.1 km) on each side. Real county shapes are rarely square, so this is a scale reference rather than a width or driving distance.
State figures are the sums of each state’s county-equivalent land measurements in the same Census release, so states and counties are compared on the same basis. Published state totals can differ slightly because of rounding. Compare all states · Counties bigger than entire states.
What stands out about Napa County?
Napa County has more land than 2,050 of the other 3,221 county equivalents in the dataset.
A median is the middle county-equivalent measurement, not the average of the largest and smallest. All three bars use the same linear scale. Very small areas may appear as a thin sliver; the labels retain their values.
Does including water change its rank?
Using land plus water places Napa County at #1,201 nationally by total area, 29 places farther from the top than its land rank. Other county equivalents gain more area when their water measurements are included.
Its water share is 5.1%, compared with a national county-equivalent median of 1.2% — 3.9 percentage points higher. This describes the statistical geography’s land/water mix, not flood exposure or developable land.
Closest positions in the national land ranking
These entries sit immediately beside Napa County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #1171 | Salt Lake County, Utah | 752.7 | Compare |
| #1172 | Napa County, California | 752 | This county |
| #1173 | Chariton County, Missouri | 751.2 | Compare |
Calculated from the same Census release as the area table. Total-area order uses original ALAND + AWATER; water shares and chart labels use published square miles. Calculation details.
Representative coordinates
The Census internal point is 38.507350, -122.325996. It represents a location inside the geography; it is not necessarily the centroid or the address of a courthouse.
Source and precision
U.S. Census Bureau, 2026 Gazetteer Files, Counties. Original ALAND: 1,947,608,455 m²; AWATER: 104,442,639 m². Rankings use ALAND; exact ties use ascending GEOID. Tables preserve Census-published square miles to three decimals, with conversions based on those values.
Common questions
How big is Napa County?
Napa County, California has 752 square miles (1,947.6 km²) of land and 40.3 square miles of water, for a total area of 792.3 square miles. It ranks #1172 of 3,222 U.S. county equivalents by land area.
Is Napa County the largest county in California?
No. Napa County ranks #48 of 58 in California by land area. The largest is San Bernardino County, with 20,068.4 square miles of land.
What counties border Napa County?
Napa County shares a land border with Solano County, Sonoma County, Yolo County, and Lake County.
What is the population of Napa County?
The Census Bureau estimates Napa County had 132,949 residents on July 1, 2025, ranking #502 of 3,222 county equivalents. That is 177 people per square mile of land.
What is the county seat of Napa County?
The county seat of Napa County is Napa.
What cities and towns are in Napa County?
Napa County has 5 incorporated places. The most populous are Napa city, American Canyon city, St. Helena city, Calistoga city, and Yountville city; 20,268 residents live outside any incorporated place.
Is Napa County part of a metropolitan area?
Yes. It is a central county of the Napa, CA Metropolitan Statistical Area.
How many ZIP codes are in Napa County?
13 ZIP Code Tabulation Areas have land in Napa County, and 10 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Napa County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 1.4 times as much land.
How many acres of land are in Napa County?
The land measurement converts to approximately 481,265 acres. Including water, total area is approximately 507,073 acres. One square mile equals 640 acres.
Why might another source show a different area?
Check whether it reports land or total area, its Census vintage, and its rounding. Our guide explains how to reconcile county area figures.
Can this establish a property boundary?
No. Statistical measurements and generalized maps do not establish property lines. Consult the relevant local surveying or land-records authority.