County outline
Where Honolulu County is located
Area breakdown
Land accounts for 27.7% of Honolulu County’s measured area and water for 72.3%. Its combined area converts to 5,610.5 square kilometers or approximately 1,386,383 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 600.791 | 1,556.042 | 384,506.2 |
| Water | 1,565.432 | 4,054.45 | 1,001,876.5 |
| Total | 2,166.223 | 5,610.492 | 1,386,382.7 |
How Honolulu County compares
By original Census land area, Honolulu County ranks #4 of 5 in Hawaii and #1622 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 0.969 times the Hawaii county-equivalent median of 619.8 square miles. It accounts for 9.4% of the combined county land area in the state.
See the complete Hawaii ranking · What counts as a county equivalent?
Population and density of Honolulu County
The Census Bureau estimates that 988,703 people lived in Honolulu County on July 1, 2025. That ranks #54 of 3,222 county equivalents nationally and #1 of 5 in Hawaii. Since the April 1, 2020 estimates base of 1,016,504, the population has declined by 27,801 (−2.7%), compared with −1.5% for Hawaii as a whole.
With 600.8 square miles of land, that is 1,646 people per square mile (635 per km²), placing Honolulu County #105 nationally for density and #1 in Hawaii. The median county equivalent has 47 people per square mile; the Hawaii median is 118. Put another way, there are about 0.389 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 1,012,334 | 1,004,238 | 993,798 | 989,698 | 990,142 | 988,703 |
| Change | — | −8,096 | −10,440 | −4,100 | +444 | −1,439 |
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 Honolulu County
Hawaii has no incorporated cities or towns: its counties provide local government directly. Honolulu County’s communities, including Urban Honolulu, are census-designated places, statistical areas the Census Bureau defines for data purposes.
Metropolitan area
Honolulu County is a central county of the Urban Honolulu, HI Metropolitan Statistical Area. Honolulu County is the area’s only county equivalent, so the metro area has the same 600.8 square miles of land. By combined land it ranks #337 of 393 metropolitan areas, and #58 by population.
ZIP codes
38 ZIP Code Tabulation Areas have land in Honolulu County, and each lies mostly inside the county.
9670196706967079671296717967309673196734967449675996762967829678696789967919679296795967979681396814968159681696817968189681996820968219682296825968269684896850968539685796858968599686096863
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 Honolulu County
Honolulu 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 Honolulu County compared with U.S. states?
Honolulu 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 11 areas the size of Honolulu County.
Another way to picture it: the same land area would fill a square about 24.5 miles (39.4 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 Honolulu County?
Honolulu County has more land than 1,600 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 Honolulu County at #289 nationally by total area, 1,333 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 72.3%, compared with a national county-equivalent median of 1.2% — 71.1 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 Honolulu County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #1621 | Clarion County, Pennsylvania | 600.8 | Compare |
| #1622 | Honolulu County, Hawaii | 600.8 | This county |
| #1623 | St. Johns County, Florida | 600.7 | 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 21.461365, -158.201974. 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: 1,556,040,300 m²; AWATER: 4,054,449,355 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 Honolulu County?
Honolulu County, Hawaii has 600.8 square miles (1,556 km²) of land and 1,565.4 square miles of water, for a total area of 2,166.2 square miles. It ranks #1622 of 3,222 U.S. county equivalents by land area.
Is Honolulu County the largest county in Hawaii?
No. Honolulu County ranks #4 of 5 in Hawaii by land area. The largest is Hawaii County, with 4,028.4 square miles of land.
What counties border Honolulu County?
None. Open water separates Honolulu County from every other county equivalent in the Census cartographic boundaries.
What is the population of Honolulu County?
The Census Bureau estimates Honolulu County had 988,703 residents on July 1, 2025, ranking #54 of 3,222 county equivalents. That is 1,646 people per square mile of land.
What is the county seat of Honolulu County?
The county seat of Honolulu County is Honolulu.
Is Honolulu County part of a metropolitan area?
Yes. It is a central county of the Urban Honolulu, HI Metropolitan Statistical Area.
How many ZIP codes are in Honolulu County?
38 ZIP Code Tabulation Areas have land in Honolulu County, and 38 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Honolulu 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 Honolulu County?
The land measurement converts to approximately 384,506 acres. Including water, total area is approximately 1,386,383 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.