North American Numbers Source-cited · ownership disclosed
Area code
650
In service
United States · since 1997

San Mateo / Palo Alto

Area code 650 serves the San Francisco Peninsula, covering most of San Mateo County and the northwestern part of Santa Clara County. It was split from 415 in 1997 and has no overlay.

The essentials Numbering data · NumberResearch · as of 2026-09-18
Place
San Mateo / Palo Alto
Type
geographic
Status
in service
In service since
1997
Projected exhaust
2039 Q3

Status, dates and counts are read from NumberResearch (NANPA / CNAC / FCC records). Assignment records show initial assignees, not the carrier serving a number today.

A · Where it is

Where 650 is

Most of San Mateo County and northwestern Santa Clara County; a small part of San Francisco..

Communities served wholly or partly by 650:

Redwood CitySan MateoMenlo ParkPalo AltoMountain ViewLos AltosHalf Moon Bay

Representative list; excludes the northernmost part of San Mateo County (415).

B · Relationships

How it relates to other codes

The codes 650 was split from, spawned, or shares its area with. A split divides the map and changes some numbers; an overlay shares the same ground and changes none — what's the difference?

Split from · 1997 415 San Francisco Split from 415 on August 2, 1997.
Related 408 San Jose Adjacent to the south (408/669).
Related 510 Oakland Adjacent to the east across the Bay (510/341).
Related 831 Monterey / Salinas Adjacent to the south.
What's changing. No overlay; ten-digit dialing since October 2021 (988 designation).
C · History

How 650 got here

1997-08-02
Area code 650 split from area code 415.
Source: Wikipedia
2021-10-24
Transitioned to ten-digit dialing to accommodate the 988 lifeline code.
Source: Wikipedia
D · Capacity

How full it is

Prefixes assigned
730
Prefixes available
70
Thousands-blocks assigned
3,251

Prefix-assignment counts describe allocation to carriers, not how many individual numbers are in use. Full technical records: NumberResearch ↗.

Compare 650 with another code →
Sources
Wikipedia ↗
Area code 650
NumberResearch.org ↗
Live status, dates, assignment counts and exhaust forecast — data as of 2026-09-18 (CC BY 4.0).

Place, relationships and history above are compiled by North American Numbers from the sources listed and last checked 2026-09-18. A check date is not an expert review — see how this is made. Flag an error.