Zip Code 98040
Mercer Island, Washington — King County
📍 ZIP code 98040 is in Mercer Island, King County, Washington.
ZIP code 98040 is located in Mercer Island, King County, Washington. It is a zip code in the Pacific (PST/PDT) Time Zone with an estimated population of 25,282. The area code for ZIP code 98040 is 206.
Quick Answer
Zip code 98040 is in Mercer Island, Washington (King County). It has a population of 25,282, median household income of $202,359, and median home value of $1,884,200.
Population
25,282
Income
$202,359
Home Value
$1,884,200
Climate
77°F / 37°F
About Zip Code 98040
Zip code 98040 is located in Mercer Island, Washington, within King County. Home to approximately 25,282 residents, this area sits at an elevation of 79 ft and falls within the Pacific (PST/PDT) timezone. The local area code is 206.
The median household income is $202,359 per year, which is above the national median of $70,784. Homes in this zip code have a median value of $1,884,200, and the cost of living index is 250 (150% above the national average of 100).
Summers average a high of 77°F while winters drop to 37°F. The area receives about 36 in of rain and 3 in of snow annually. The zip code covers 6.4 square miles of land area and 6.5 square miles of water.
Key Statistics
25,282
$202,359
$1,884,200
Pacific (PST/PDT)
206
79 ft
6.4 sq mi
45.8
10,454
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Compare With Nearby Zip Codes
| Metric | 98040 | 98118 | 98144 | 98006 | 98004 | 98108 |
|---|---|---|---|---|---|---|
| City | Mercer Island, WA | Seattle, WA | Seattle, WA | Bellevue, WA | Bellevue, WA | Seattle, WA |
| Population | 25,282 | 49,560 | 33,048 | 40,770 | 39,435 | 24,430 |
| Median Income | $202,359 | $109,085 | $94,051 | $197,344 | $176,367 | $90,806 |
| Home Value | $1,884,200 | $746,400 | $890,400 | $1,233,500 | $2M+ | $693,500 |
| Cost of Living | 250 | 213 | 236 | 250 | 250 | 193 |
| Median Age | 45.8 | 38 | 38.2 | 42.3 | 38.4 | 37 |
Cost of Living
100 = National Average. Mercer Island's cost of living is 150% above the national average.
vs. State Avg
Above
Affordability
Expensive
Income-to-Home
9.3x
Demographics
Zip code 98040 has a population of 25,282 people with a median age of 45.8. There are 10,454 housing units in this area.
Racial & Ethnic Composition
Source: U.S. Census Bureau American Community Survey estimates.
Population History
Mercer Island (98040) population trend from 2010 to 2024
↑ 85.6%Source: U.S. Census Bureau estimates and American Community Survey data.
Climate & Weather
77°F
37°F
36 in
3 in
Mercer Island experiences mild summers with average highs around 77°F. Winters are mild with lows averaging 37°F. The area receives about 3 in of snow per year.
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Housing & Economy
Median Home Value
$1,884,200
Median Household Income
$202,359
With 10,454 housing units across 6.4 square miles, 98040 has a housing density of 1,633 units per square mile. The home price-to-income ratio is 9.3x.
Location & Geography
Latitude
47.5640°
Longitude
-122.2312°
Land Area
6.4 sq mi
Water Area
6.5 sq mi
Nearby Zip Codes
Zip codes closest to 98040 (Mercer Island, WA) with distances:
ZIP Codes with Similar Income Nationwide
The five U.S. ZIP codes whose median household income is closest to 98040's $202,359. A way to compare Mercer Island to economically similar communities elsewhere in the country.
Computed from U.S. Census Bureau ACS 5-Year Estimates by the Zip Code Near Me Data Team.
ZIP Codes with Similar Demographics
The five U.S. ZIP codes whose racial and ethnic composition most closely matches 98040 (Mercer Island, WA). Similarity is measured by cosine distance on the five-category ACS demographic vector.
Computed from U.S. Census Bureau ACS 5-Year Estimates by the Zip Code Near Me Data Team.
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People Also Ask
What zip code is Mercer Island, Washington?
Mercer Island, Washington uses zip code 98040.
What county is zip code 98040 in?
Zip code 98040 is located in King County, Washington.
What is the population of zip code 98040?
The population of zip code 98040 is 25,282 with a median age of 45.8.
Is 98040 in Mercer Island, Washington?
Yes, zip code 98040 is in Mercer Island, King County, Washington. The area code is 206.
Frequently Asked Questions
What city is zip code 98040 in?
Zip code 98040 is in Mercer Island, Washington. It is part of King County and uses the Pacific (PST/PDT) timezone.
What is zip code 98040?
Zip code 98040 is a U.S. postal code in Mercer Island, Washington (King County). It has a population of 25,282 and covers 6.4 square miles.
What is the population of zip code 98040?
The population of zip code 98040 (Mercer Island, WA) is 25,282 with a median age of 45.8. There are approximately 10,454 housing units in this area.
What is the median income in zip code 98040?
The median household income in zip code 98040 (Mercer Island, WA) is $202,359 per year. The cost of living index is 250 (100 = national average).
What is the average home price in zip code 98040?
The median home value in zip code 98040 (Mercer Island, WA) is $1,884,200. The cost of living index is 250 compared to the national average of 100.
What county is zip code 98040 in?
Zip code 98040 is located in King County, Washington. The primary city is Mercer Island.
What is the area code for zip code 98040?
Zip code 98040 in Mercer Island, WA uses area code 206. It is located in the Pacific (PST/PDT) timezone.
Is zip code 98040 a good place to live?
Zip code 98040 (Mercer Island, WA) has a cost of living index of 250 (100 = national average), a median household income of $202,359, and median home values of $1,884,200. The median age is 45.8. Visit the full page for demographics, climate, and nearby zip code comparisons.
What is the cost of living in zip code 98040?
The cost of living index for zip code 98040 (Mercer Island, WA) is 250, where 100 represents the national average. This area is above the national average. Median home value: $1,884,200.
What schools serve zip code 98040?
Zip code 98040 in Mercer Island, Washington is served by the local school district of King County. For specific school information, check your state's department of education or GreatSchools.org.
All demographic data on this page is sourced from the U.S. Census Bureau American Community Survey (ACS) 5-Year Estimates. ZIP code boundary and delivery data is sourced from the United States Postal Service (USPS). Data is updated periodically and may not reflect the most current figures. Census Bureau ZIP Code Tabulation Areas (ZCTAs) may differ slightly from USPS ZIP code boundaries.
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Data Sources
- Population, income, housing, age, and demographics
- U.S. Census Bureau, American Community Survey 5-Year Estimates, 2019-2023 vintage.
- ZIP to city and county mapping
- USPS and HUD-USPS ZIP-County Crosswalk.
- Time zones and area codes
- IANA tz database and NANPA.
- Elevation
- U.S. Geological Survey National Elevation Dataset (NED), via the USGS Elevation Point Query Service. Mapped to each ZCTA centroid coordinates. Last refreshed 2026-05-19.
- Last refreshed
- 2026-05-18.