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ZIP stands for Zone Improvement Plan. The codes went live on July 1, 1963.The lowest ZIP code is 00501 — the IRS in Holtsville, New York.The highest ZIP code is 99950, in Ketchikan, Alaska.Type 07734 into a calculator and turn it upside down: hELLO. It is Keansburg, New Jersey.12345 belongs to one company: General Electric in Schenectady, New York.The first digit is a region: 0 is New England and New Jersey, 9 is the West Coast, Alaska and Hawaii.Mr. ZIP, the cartoon mailman, was the mascot that sold the idea to America.ZIP+4 arrived in 1983 and can narrow a ZIP down to one side of one block.A ZIP code is a mail route, not a place: plenty of them cross county and even state lines.Play ZIP Hunt: guess the secret ZIP code of the day in six tries.
zipcodes.pro — ZIP/94403

94403

ZIP 94403 is in San Mateo, California, in San Mateo County; area code 650; Pacific time. San Mateo has 5 ZIP codes; the others are 94401, 94402, 94404 and 94497.

Type
Standard
Time zone
America/Los_Angeles
County
San Mateo
Population
43,276
Coordinates
37.5384, -122.3054
☼ Live from 94403 — San Mateo, CA

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Local time: —

Where 94403 is

Approximate ZIP boundary (Census ZCTA 2020). ZIP codes are mail routes, not areas, so the shape shown is the Census tabulation area that approximates it.

★ Weird and wonderful facts about 94403
  • 🔢 Type 94403 into a pocket calculator and turn it upside down: EOhhG — not quite a word, sorry.
  • ➕ As a number, 94,403 = 67 × 1409. Its digits add up to 20, a total 2,586 other ZIP codes share.
  • 💾In binary, the way a computer stores it: 10111000011000011
  • 🏠 Its numerical neighbours: 94402 (San Mateo, CA, 1 mi away) and 94404 (San Mateo, CA, 2 mi away).
  • 🔄 Backwards, 94403 becomes 30449 — and that is a real ZIP code: Oliver, GA, 2,314 miles away.
  • 👥 24 other ZIP codes are made of exactly the same digits (03449, 04349, 04493, 04943, 30449, 39044, …). The farthest-flung twin is 04493 in West Enfield, ME, 2,784 miles away.
  • 🧭 Farther south than 61% of all ZIP codes, and farther west than 96%.
  • 🎯1,286 miles west of the geographic center of the Lower 48, near Lebanon, Kansas.
  • 🌏 Dig straight through the Earth from 94403 and you would come out at 37.54°S, 57.69°E — 1,027 miles from Port-aux-Français, French Southern Territories, the nearest big city to that spot.
  • ☀Longest day of the year: 14h 45m of daylight. Shortest: 9h 34m.
  • 📏 At 5.6 square miles of land, 94403 is bigger than 20% of ZIP codes — room for about 4.3 Central Parks.
🌙 The sky over 94403 today
  • Working out the sun…
🌋 Shake report
  • Checking the USGS…

Source: USGS.

People and housing

Population43,276This ZIP43,276
Households16,414This ZIP16,414
Housing units17,799This ZIP17,799
Median age38.9This ZIP38.9California37.9US 38.9
Median household income$174,917This ZIP$174,917California$99,122US $80,734
Median home value$1,746,300This ZIP$1,746,300California$734,700US $332,700
Median gross rent$3,263This ZIP$3,263California$2,036US $1,413
Bachelor's degree or higher60.6%This ZIP60.6%
Mean commute26.3 minThis ZIP26.3 min
Population density7,682.6 / sq miThis ZIP7,682.6 / sq mi

Business and tax activity

Business establishments1,204This ZIP1,204
Employees32,578This ZIP32,578
Annual payroll$5,451,196,000This ZIP$5,451,196,000
Tax returns filed21,690This ZIP21,690
Total adjusted gross income$4,265,377,000This ZIP$4,265,377,000

Land area

Land area5.63 sq miThis ZIP5.63 sq mi
Water area0.16 sq miThis ZIP0.16 sq mi

Other place names in 94403

Census places whose land this ZIP code overlaps. The Postal Service may accept other city names in an address, too.

ZIP codes near 94403

ZIPCityDistance
94497 San Mateo, CA 1.2 mi
94402 San Mateo, CA 1.4 mi
94002 Belmont, CA 1.8 mi
94404 San Mateo, CA 2.4 mi
94401 San Mateo, CA 2.7 mi
94065 Redwood City, CA 3.1 mi
94070 San Carlos, CA 3.4 mi
94010 Burlingame, CA 4.5 mi
94011 Burlingame, CA 4.6 mi
94061 Redwood City, CA 6.5 mi

Find every ZIP code within 10 miles of 94403 →

Questions about this ZIP code

Where is ZIP code 94403?

94403 is in San Mateo, California, in San Mateo County, part of the San Francisco-Oakland-Fremont, CA metropolitan area. Its published point location is 37.5384, -122.3054.

What county is 94403 in?

94403 lies in San Mateo County.

What area code is 94403?

San Mateo uses area code 650, from NANPA's telephone records.

What time zone is 94403 in?

94403 uses America/Los_Angeles.

How many people live in 94403?

About 43,276 people live in ZIP code 94403, in 16,414 households, at 7,682.6 people per square mile. These are American Community Survey 5-year estimates for the ZIP Code Tabulation Area, not a headcount.

What is the median household income in 94403?

$174,917 a year, against $99,122 across California.

What ZIP codes are near 94403?

The closest are 94497 (1.2 mi), 94402 (1.4 mi), 94002 (1.8 mi), 94404 (2.4 mi) and 94401 (2.7 mi).

Is 94403 a PO Box ZIP code?

94403 is a standard ZIP code. A normal ZIP code with street delivery.

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Cite this page

zipcodes.pro. “94403 ZIP Code — San Mateo, California (San Mateo County).” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/zip/94403

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