County outline
Where Kauai County is located
Area breakdown
Land accounts for 48.9% of Kauai County’s measured area and water for 51.1%. Its combined area converts to 3,279.7 square kilometers or approximately 810,441 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 619.84 | 1,605.378 | 396,697.6 |
| Water | 646.474 | 1,674.36 | 413,743.4 |
| Total | 1,266.314 | 3,279.738 | 810,441 |
How Kauai County compares
By original Census land area, Kauai County ranks #3 of 5 in Hawaii and #1554 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 1 times the Hawaii county-equivalent median of 619.8 square miles. It accounts for 9.7% of the combined county land area in the state.
See the complete Hawaii ranking · What counts as a county equivalent?
Population and density of Kauai County
The Census Bureau estimates that 73,400 people lived in Kauai County on July 1, 2025. That ranks #772 of 3,222 county equivalents nationally and #4 of 5 in Hawaii. Since the April 1, 2020 estimates base of 73,295, the population has grown by 105 (+0.1%), compared with −1.5% for Hawaii as a whole.
With 619.8 square miles of land, that is 118 people per square mile (46 per km²), placing Kauai County #882 nationally for density and #3 in Hawaii. The median county equivalent has 47 people per square mile; the Hawaii median is 118. Put another way, there are about 5.4 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 73,210 | 73,843 | 73,707 | 73,672 | 73,440 | 73,400 |
| Change | — | +633 | −136 | −35 | −232 | −40 |
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 Kauai County
Hawaii has no incorporated cities or towns: its counties provide local government directly. Kauai County’s communities are census-designated places, statistical areas the Census Bureau defines for data purposes.
Metropolitan area
Kauai County is a central county of the Kapaa, HI Micropolitan Statistical Area. Kauai County is the area’s only county equivalent, so the micro area has the same 619.8 square miles of land. By combined land it ranks #344 of 542 micropolitan areas, and #95 by population.
ZIP codes
16 ZIP Code Tabulation Areas have land in Kauai County, and each lies mostly inside the county.
96703967059671496716967229674196746967479675196752967549675696765967669676996796
ZIP Code Tabulation Areas are the Census Bureau’s approximations of USPS ZIP Code service areas, from the 2020 Census relationship files. Post-office-box and single-address ZIP Codes have no tabulation area.
Counties bordering Kauai County
Kauai County has no land border with another county equivalent in the Census cartographic boundaries: open water separates it from every other county equivalent. Its nearest entries in the national land ranking are listed below, and the Hawaii directory lists every county equivalent in the state.
How big is Kauai County compared with U.S. states?
Kauai County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.7 times as much. Hawaii’s county land could hold about 10 areas the size of Kauai County.
Another way to picture it: the same land area would fill a square about 24.9 miles (40.1 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 Kauai County?
Kauai County has more land than 1,668 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 Kauai County at #553 nationally by total area, 1,001 places closer to the top than its land rank. The water assigned to this geography moves it ahead of some county equivalents with more land.
Its water share is 51.1%, compared with a national county-equivalent median of 1.2% — 49.9 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 Kauai County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #1553 | Schoharie County, New York | 621.8 | Compare |
| #1554 | Kauai County, Hawaii | 619.8 | This county |
| #1555 | Rutherford County, Tennessee | 619.5 | 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 22.012038, -159.705965. 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: 1,605,377,469 m²; AWATER: 1,674,359,128 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 Kauai County?
Kauai County, Hawaii has 619.8 square miles (1,605.4 km²) of land and 646.5 square miles of water, for a total area of 1,266.3 square miles. It ranks #1554 of 3,222 U.S. county equivalents by land area.
Is Kauai County the largest county in Hawaii?
No. Kauai County ranks #3 of 5 in Hawaii by land area. The largest is Hawaii County, with 4,028.4 square miles of land.
What counties border Kauai County?
None. Open water separates Kauai County from every other county equivalent in the Census cartographic boundaries.
What is the population of Kauai County?
The Census Bureau estimates Kauai County had 73,400 residents on July 1, 2025, ranking #772 of 3,222 county equivalents. That is 118 people per square mile of land.
What is the county seat of Kauai County?
The county seat of Kauai County is Līhuʻe.
Is Kauai County part of a metropolitan area?
Yes. It is a central county of the Kapaa, HI Micropolitan Statistical Area.
How many ZIP codes are in Kauai County?
16 ZIP Code Tabulation Areas have land in Kauai County, and 16 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Kauai County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 1.7 times as much land.
How many acres of land are in Kauai County?
The land measurement converts to approximately 396,698 acres. Including water, total area is approximately 810,441 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.