Gaithersburg, MD ZIP Codes, Area Codes and Address Format

City guides  |  July 31, 2026  |  2 min read

Looking up ZIP codes or writing an address in Gaithersburg, Maryland? Below is a practical reference built from postal data for the city.

State

Maryland (MD)

County

Montgomery County

Standard ZIP codes

4

Time zone

Eastern

Gaithersburg ZIP codes

These are the standard delivery ZIP codes for Gaithersburg. The city has 9 ZIP codes in total when PO Box and unique codes are included.

• 20877
• 20878
• 20879
• 20882

Area codes in Gaithersburg

Gaithersburg phone numbers use 227, 240, 301, 410, 443 and 667. With more than one code in use, residents on the same street can have different area codes.

Sample Gaithersburg addresses

The street lines are invented; the city, state and ZIP codes are real. Use them for form testing, mockups and training materials, never for real orders.

How to write an address in Gaithersburg

• End the address with GAITHERSBURG, MD and the five-digit ZIP code.
• Put apartment or suite numbers at the end of the street line.
• Use USPS abbreviations such as ST, AVE and BLVD.
• Match the ZIP code to the street. Gaithersburg has 4 codes, so the city name alone is not enough.

Other cities in Montgomery County

Silver Spring, Rockville, Bethesda, Germantown

More Maryland cities

Hyattsville, Baltimore, Bethesda, Laurel, Silver Spring, or see all Maryland cities.