94528 ZIP Code — Diablo, CA

Contra Costa County, California

ZIP code 94528 is located in Diablo, California, within Contra Costa County. It covers approximately 1.15 square miles and serves a population of 726 residents. This is a standard ZIP code in the Pacific (PT) timezone, served by area code 925.

About ZIP code 94528

The housing stock consists of predominantly single-family detached homes. Most homes were built in the 1950s, giving the area an established character. Median home value is $2,000,000.

The gap between median ($250,001) and mean household income suggests income inequality — a small number of higher earners pull the average up. 33% of households receive Social Security income, suggesting a notable retiree or disability population.

The dominant occupation class is management, business, and professional, with construction as the leading industry.

Educational attainment is high — 73% of residents hold a bachelor's degree or higher, well above the national average of 33%.

Notable community characteristics include a notable veteran presence at 11% of civilians, above the national average of 7%.

Overall, ZIP code 94528 reflects a community defined by a highly educated population, a strong veteran community, high homeownership, and a significant Social Security-dependent population.

726

population

1.15

sq mi land

Standard

ZIP type

Pacific (PT)

timezone

94528 ZIP code map

Cities in ZIP code 94528

Below are the cities the US Postal Service accepts for ZIP code 94528. Using any city not on this list may result in mail delivery delays.

City	Status
Diablo	Acceptable

Demographics updated 05/2026

Population
Total population	726
Population density	631 / sq mi
State FIPS	06
County FIPS	013

Geography
Land area	1.15 sq mi
Water area	0.00 sq mi
Latitude	37.8414
Longitude	-121.9628
Timezone	Pacific (PT)
Area code	925

Total population by age

Gender

Race & ethnicity

Economics updated 05/2026

Household income

Income range	This ZIP	County avg	State avg
Under $50k	12.7%	23.2%	32.6%
$50k – $100k	19.4%	25.1%	27.7%
$100k – $200k	15.6%	31.3%	26.4%
Over $200k	52.3%	20.4%	13.3%

Demographics & statistics

726

Population

631

People per sq mi

37.4

Median age

$250,001

Median household income

$119,948

Per capita income

$2,000,000

Median home value

Median monthly rent

100.0%

Home ownership

17.1%

Poverty rate

16.5%

Unemployment

268

Housing units

73.0%

Bachelor's or higher

Age distribution

Male Female

Under 5

5–9

15–19

20–24

35–44

45–54

55–59

75–84

← Male

Female →

Age summary

Group	Count	%
Under 18	231	31.8%
18 and over	495	68.2%
65 and over	149	20.5%
Median age	37.4 years

Race & ethnicity

White 86%

Two or more races 7.1%

Hispanic or Latino 4.7%

Asian 2.2%

Group	Count	%
White	655	86%
Two or more races	54	7.1%
Hispanic or Latino	36	4.7%
Asian	17	2.2%

Household income

Income range	This ZIP	County avg	State avg
Under $50k	12.7%	23.2%	32.6%
$50k – $100k	19.4%	25.1%	27.7%
$100k – $200k	15.6%	31.3%	26.4%
Over $200k	52.3%	20.4%	13.3%

Under $10k 15.7%

$25k–$35k 10.4%

$35k–$50k 8.3%

$50k–$75k 7.8%

$200k+ 57.8%

Range	% of households
Under $10k	15.7%
$25k–$35k	10.4%
$35k–$50k	8.3%
$50k–$75k	7.8%
$200k+	57.8%
Median income	$250,001

Housing

Home values

$1M+ 100.0%

Housing overview

Metric	Value
Median home value	$2,000,000
Median rent / month	$0
Owner occupied	100.0%
Renter occupied	0.0%
Vacant	14.2%
Single-family detached	100.0%
Large apartment buildings	0.0%
Mobile homes	0.0%
Median rooms	8.4
Avg household size (owned)	3.16

Year built

Era	%
2020 or later	0.0%
2010–2019	0.0%
2000–2009	25.4%
1990–1999	16.4%
1980–1989	11.9%
1970–1979	0.0%
1960–1969	0.0%
1950–1959	46.3%
1940–1949	0.0%
1939 or earlier	0.0%

Bedrooms

Size	% of units
No bedroom (studio)	0.0%
1 bedroom	0.0%
2 bedrooms	0.0%
3 bedrooms	16.4%
4 bedrooms	51.5%
5+ bedrooms	32.1%

Vehicles per household

Vehicles	% of households
No vehicle	0.0%
1 vehicle	0.0%
2 vehicles	14.3%
3 or more	85.7%

Heating fuel

Fuel type	%
Utility gas	92.2%
Electricity	7.8%

Households & families

Household type	Count	%
Married-couple family	194	84.3%
Cohabiting couple	0	0.0%
Male householder, no spouse	0	0.0%
Female householder, no spouse	36	15.7%
Households with children under 18	99	43.0%
Households with seniors (65+)	75	32.6%
Average household size	3.16

Marital status

Status	Male	Female
Never married	24.4%	16.9%
Married	75.6%	69.0%
Separated	0.0%	0.0%
Widowed	0.0%	14.1%
Divorced	0.0%	0.0%

Education

Less than 9th grade 0.0%

Some HS, no diploma 0.0%

HS graduate 4.7%

Some college, no degree 10.6%

Associate's degree 11.8%

Bachelor's degree 13.0%

Graduate / professional 60.0%

Metric	%
HS diploma or higher	100.0%
Bachelor's or higher	73.0%

School enrollment (ages 3–17)

Type	Count	%
Nursery / preschool	67	21.8%
Kindergarten	72	23.5%
Elementary school	62	20.2%
High school	63	20.5%
College / grad school	43	14.0%

Employment

Industry of employment

Construction 37.2%

Professional & management 32.6%

Arts, food & hospitality 20.6%

Finance & real estate 9.6%

Occupation

Category	%
Management, business & arts	79.4%
Service	0.0%
Sales & office	20.6%
Natural resources & construction	0.0%
Production & transportation	0.0%

Employment type

Type	%
Private sector	100.0%
Government	0.0%
Self-employed	0.0%
Unpaid family workers	0.0%

Commute

Method	%
Drive alone	91.7%
Carpool	0.0%
Public transit	0.0%
Walk	0.0%
Work from home	8.3%
Other means	0.0%
Avg commute (minutes)	0.0

Poverty

All people 17.1%

Under 18 years 0.0%

18 and over 25.1%

Married-couple families 0.0%

Female-led households 100.0%

Income support

Source	% of households
Social Security	32.6%
Retirement income	24.3%
Supplemental Security	0.0%
Cash public assistance	0.0%
Food stamps / SNAP	0.0%

Health indicators

Condition	%
Obesity	25.6%
High blood pressure	30.8%
High cholesterol	35.1%
Diabetes	9.0%
Heart disease	6.6%
Stroke	2.7%
Asthma	8.8%
Arthritis	27.3%
Kidney disease	2.9%
Pulmonary disease	5.3%
Cancer	9.6%

Behavior / access	%
Smoking	6.9%
Binge drinking	16.0%
No physical activity	13.5%
Less than 7 hrs sleep	25.5%
Depression	15.7%
Fair or poor health	9.5%
Poor mental health	10.4%
Poor physical health	8.1%
No health insurance	4.7%
Visited doctor (checkup)	71.2%
Visited dentist	79.8%
Cholesterol screening	96.1%
Teeth loss	5.2%

Veterans & disability

Veterans	Count	%
Civilian veterans	56	11.3%

Disability	%
Any disability	3.3%
Under 18	0.0%
18–64 years	0.0%
65 and over	16.1%

Health insurance coverage

Type	%
Private insurance	100.0%
Public insurance	20.5%
No insurance	0.0%
Uninsured under 19	0.0%

Language & origin

Language spoken at home (age 5+)

Language	Count	%
English only	647	89.1%
Spanish	0	0.0%
Other Indo-European	0	0.0%
Asian & Pacific Islander	0	0.0%
Other languages	0	0.0%

Place of birth & citizenship

Origin	Count	%
Native born (US)	673	92.7%
Born in same state	673	92.7%
Born in different state	342	47.1%
Foreign born	0	0.0%
Naturalized citizen	53	7.3%
Not a US citizen	53	100.0%

Ancestry

Ancestry	Count	%
French	100	13.8%

Ancestry	Count	%
Italian	60	8.3%

Technology access

Metric	% of households
Computer access	31.7%
Internet access	100.0%

Source: U.S. Census Bureau, American Community Survey 2025 estimates.

Frequently asked questions about ZIP code 94528

What city is ZIP code 94528 in?

ZIP code 94528 is primarily assigned to Diablo, California.

What county is ZIP code 94528 in?

ZIP code 94528 falls within Contra Costa County, California.

How educated is the population of ZIP code 94528?

73% of residents hold a bachelor's degree or higher — well above the national average of ~33%, reflecting a highly educated population.

Is ZIP code 94528 family-oriented?

32% of residents in ZIP code 94528 are under 18, reflecting a younger, family-oriented community.

What is the poverty rate in ZIP code 94528?

17% of residents in ZIP code 94528 live below the poverty line, above the national average.

Does ZIP code 94528 have a large veteran population?

11% of civilians in ZIP code 94528 are veterans, above the national average of ~7%.

What timezone is ZIP code 94528 in?

ZIP code 94528 observes the PST timezone.