County outline
Where Waukesha County is located
Area breakdown
Land accounts for 94.7% of Waukesha County’s measured area and water for 5.3%. Its combined area converts to 1,503.6 square kilometers or approximately 371,544 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 549.727 | 1,423.786 | 351,825.3 |
| Water | 30.811 | 79.8 | 19,719 |
| Total | 580.538 | 1,503.587 | 371,544.3 |
How Waukesha County compares
By original Census land area, Waukesha County ranks #55 of 72 in Wisconsin and #1899 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 0.73 times the Wisconsin county-equivalent median of 753 square miles. It accounts for 1% of the combined county land area in the state.
See the complete Wisconsin ranking · What counts as a county equivalent?
Population and density of Waukesha County
The Census Bureau estimates that 417,210 people lived in Waukesha County on July 1, 2025. That ranks #185 of 3,222 county equivalents nationally and #3 of 72 in Wisconsin. Since the April 1, 2020 estimates base of 406,989, the population has grown by 10,221 (+2.5%), compared with +1.3% for Wisconsin as a whole.
With 549.7 square miles of land, that is 759 people per square mile (293 per km²), placing Waukesha County #241 nationally for density and #2 in Wisconsin. The median county equivalent has 47 people per square mile; the Wisconsin median is 51. Put another way, there are about 0.843 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 407,506 | 409,199 | 410,846 | 413,581 | 415,766 | 417,210 |
| Change | — | +1,693 | +1,647 | +2,735 | +2,185 | +1,444 |
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 Waukesha County
Waukesha County is divided into 38 cities and towns. In Wisconsin, county subdivisions are local governments, and together they cover all of the county’s land and residents.
The most populous is Waukesha city, with 70,872 residents (17% of the county). The largest by land is New Berlin city, at 36.4 mi², or 6.6% of the county’s land. Among those with at least 1,000 residents in 2020, Lannon village grew fastest since then (+52.1%).
| County subdivision | Population 2025 | Since 2020 | Land mi² | Share of county land |
|---|---|---|---|---|
| Waukesha cityCounty seat | 70,872 | −0.4% | 25.5 | 4.6% |
| Brookfield city | 41,448 | −0% | 27.4 | 5% |
| Menomonee Falls village | 41,291 | +7.2% | 32.9 | 6% |
| New Berlin city | 39,953 | −1.2% | 36.4 | 6.6% |
| Muskego city | 25,602 | +2.2% | 31.6 | 5.7% |
| Oconomowoc city | 20,119 | +10.7% | 11.8 | 2.1% |
| Pewaukee city | 16,375 | +2.8% | 19.5 | 3.6% |
| Sussex village | 12,779 | +10.1% | 8.446 | 1.5% |
| Lisbon village | 11,150 | +7.9% | 26.3 | 4.8% |
| Hartland village | 10,740 | +13.1% | 5.46 | 1% |
| Oconomowoc town | 8,849 | +0.2% | 0.503 | 0.1% |
| Waukesha villageCounty seat | 8,507 | +0.5% | 20.6 | 3.7% |
| Mukwonago village | 8,328 | +3.7% | 6.226 | 1.1% |
| Merton town | 8,319 | +0.2% | 24.4 | 4.4% |
| Pewaukee village | 8,216 | −0.1% | 4.119 | 0.7% |
Show the other 23 subdivisions
| Name | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Delafield town | 8,012 | −1% | 18.4 |
| Mukwonago town | 7,763 | −0.4% | 29.4 |
| Vernon village | 7,464 | −0.1% | 30 |
| Delafield city | 7,314 | +1.7% | 9.412 |
| Genesee town | 7,235 | +0.9% | 30.3 |
| Brookfield town | 6,515 | +0.7% | 5.025 |
| Elm Grove village | 6,354 | −2.5% | 3.261 |
| Summit village | 5,323 | +11.1% | 20.7 |
| Merton village | 3,676 | +6.6% | 3.338 |
| Ottawa town | 3,642 | −0.1% | 32.7 |
| Eagle town | 3,536 | +1.6% | 33.6 |
| Wales village | 2,885 | +0.9% | 3.226 |
| Dousman village | 2,665 | +9.8% | 3.046 |
| North Prairie village | 2,193 | −0.4% | 2.752 |
| Eagle village | 2,115 | +2.2% | 1.736 |
| Lannon village | 2,057 | +52.1% | 2.474 |
| Butler village | 1,752 | −1.8% | 0.782 |
| Big Bend village | 1,498 | +0.5% | 3.251 |
| Nashotah village | 1,298 | −1.6% | 1.627 |
| Oconomowoc Lake village | 570 | −0.3% | 1.921 |
| Chenequa village | 521 | +0.8% | 3.461 |
| Lac La Belle village | 274 | −1.1% | 28 |
| Milwaukee city | 0 | — | 0.069 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each subdivision inside Waukesha County. Land: 2026 Census Gazetteer. How communities are listed.
Metropolitan area
Waukesha County is a central county of the Milwaukee-Waukesha, WI Metropolitan Statistical Area. Its 4 county equivalents have 1,575,010 residents on 1,454.8 square miles of land; Waukesha County accounts for 37.8% of the land and 26.5% of the residents. By combined land it ranks #225 of 393 metropolitan areas, and #42 by population. It belongs to the Milwaukee-Racine-Waukesha, WI Combined Statistical Area.
| County equivalent | Population 2025 | Land mi² |
|---|---|---|
| Milwaukee County | 924,216 | 241.5 |
| Waukesha County | 417,210 | 549.7 |
| Washington County | 139,238 | 430.6 |
| Ozaukee County | 94,346 | 233 |
ZIP codes
31 ZIP Code Tabulation Areas have land in Waukesha County; 26 of them have most of their land inside the county, and the others mainly cover neighboring areas.
53005530075301753018530295303653045530465305153058530665306953072530895310353118531195312253127531465314953150531515315353183531855318653188531895322553227
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 Waukesha County
Waukesha County shares a land border with 6 county equivalents. It has more land than 3 of them. The largest neighbor is Dodge County (875.7 mi²) and the smallest is Milwaukee County (241.5 mi²). Together with its neighbors, Waukesha County forms a block of 3,542.1 mi² of land, of which it holds 15.5%.
| Bordering county equivalent | Land mi² | Size vs. Waukesha | Compare |
|---|---|---|---|
| Dodge County | 875.7 | 1.6× larger | Compare |
| Jefferson County | 556.5 | about the same | Compare |
| Walworth County | 555.4 | about the same | Compare |
| Washington County | 430.6 | 1.3× smaller | Compare |
| Racine County | 332.6 | 1.7× smaller | Compare |
| Milwaukee County | 241.5 | 2.3× smaller | Compare |
How big is Waukesha County compared with U.S. states?
Waukesha County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.9 times as much. Wisconsin’s county land could hold about 99 areas the size of Waukesha County.
Another way to picture it: the same land area would fill a square about 23.4 miles (37.7 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 Waukesha County?
Waukesha County has more land than 1,323 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 Waukesha County at #1,826 nationally by total area, 73 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 5.3%, compared with a national county-equivalent median of 1.2% — 4.1 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 Waukesha County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #1898 | Iron County, Missouri | 550.3 | Compare |
| #1899 | Waukesha County, Wisconsin | 549.7 | This county |
| #1900 | Iosco County, Michigan | 549.5 | 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 43.017695, -88.299725. 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: 1,423,787,385 m²; AWATER: 79,799,928 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 Waukesha County?
Waukesha County, Wisconsin has 549.7 square miles (1,423.8 km²) of land and 30.8 square miles of water, for a total area of 580.5 square miles. It ranks #1899 of 3,222 U.S. county equivalents by land area.
Is Waukesha County the largest county in Wisconsin?
No. Waukesha County ranks #55 of 72 in Wisconsin by land area. The largest is Marathon County, with 1,545.2 square miles of land.
What counties border Waukesha County?
Waukesha County shares a land border with Jefferson County, Milwaukee County, Washington County, Racine County, Walworth County, and Dodge County.
What is the population of Waukesha County?
The Census Bureau estimates Waukesha County had 417,210 residents on July 1, 2025, ranking #185 of 3,222 county equivalents. That is 759 people per square mile of land.
What is the county seat of Waukesha County?
The county seat of Waukesha County is Waukesha.
What cities and towns are in Waukesha County?
Waukesha County has 38 county subdivisions (cities, towns and townships). The most populous five are Waukesha city, Brookfield city, Menomonee Falls village, New Berlin city, and Muskego city.
Is Waukesha County part of a metropolitan area?
Yes. It is a central county of the Milwaukee-Waukesha, WI Metropolitan Statistical Area, which has 4 county equivalents and 1,575,010 residents.
How many ZIP codes are in Waukesha County?
31 ZIP Code Tabulation Areas have land in Waukesha County, and 26 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Waukesha County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 1.9 times as much land.
How many acres of land are in Waukesha County?
The land measurement converts to approximately 351,825 acres. Including water, total area is approximately 371,544 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.