The 650 area code serves the San Francisco Peninsula, California — the corridor of communities between San Francisco and Silicon Valley. Created in 1997, 650 covers San Mateo County and adjacent areas, including many of the region’s technology and biotech hubs. If a 650 number has appeared on your caller ID, this guide explains where it comes from, how to dial it, and how to stay safe from spoofed calls.
Quick Summary: Area Code 650 at a Glance
| Detail | Information |
|---|---|
| Area Code | 650 |
| State | California (CA) |
| Major Cities | San Mateo, Redwood City, Palo Alto, Daly City |
| Time Zone | Pacific Time (PT) |
| Country Code | +1 (USA) |
| Overlay Codes | None (single area code) |
Geographic Coverage & Major Cities
Area code 650 covers most of San Mateo County and the northwestern edge of Santa Clara County, running down the San Francisco Peninsula between the city of San Francisco and San Jose. It borders San Francisco Bay to the east and the Pacific coast to the west.
Cities and communities served by the 650 area code include:
- San Mateo and Redwood City — the county’s central commercial hubs
- Palo Alto and Menlo Park — home to Stanford University and leading tech and venture-capital firms
- Daly City and South San Francisco — the northern Peninsula, near San Francisco
- Burlingame, San Bruno, and Half Moon Bay — bayside and coastal communities
Because it spans the Peninsula’s tech and biotech corridor, a 650 number carries a strong Bay Area professional identity.
A Brief History of Area Code 650
Area code 650 was created in 1997, split from 415 as the San Francisco Bay Area’s demand for numbers grew. The split kept 415 for San Francisco and Marin County and assigned 650 to the Peninsula. To date, 650 has remained a single area code without an overlay, though 10-digit dialing is now standard across California.
Time Zone & Best Time to Call
Numbers in the 650 area code use Pacific Time (PT). The region observes Daylight Saving Time, shifting from PST (UTC−8) to PDT (UTC−7) between March and November each year.
How to Dial Phone Numbers in Area Code 650
Ten-digit dialing is now standard throughout California, so always include the area code.
Calling within the United States or Canada
- 10-digit dialing: Dial the full number — 650-XXX-XXXX.
- 11-digit dialing: You can also dial 1-650-XXX-XXXX; the leading 1 is the NANP country code.
Calling from outside the United States
- Format: [exit code] + 1 + 650 + XXX + XXXX
- From the UK, Europe, or most of Asia/Africa: 00 1 650 XXX XXXX
- From any mobile phone worldwide: +1 650 XXX XXXX
Is Area Code 650 a Scam? Safety & Protection Tips
Area code 650 is a legitimate California area code — a call from it is not fraudulent by default. However, scammers frequently spoof the code, faking the caller ID so their number appears to come from a trusted local Peninsula line. Neighbor spoofing, which mimics your own number’s first six digits, is especially common.
Common scam tactics linked to this region
| Scam type | What to watch for |
|---|---|
| Tech-company impersonation | Fake “account security” or software-support pitches |
| Investment & crypto scams | Unsolicited “opportunities” promising guaranteed returns |
| Government impersonation | Callers posing as the IRS or SSA threatening legal action |
| Bank & card fraud alerts | Claims of “suspicious activity” seeking your account details |
How to report, block, and look up 650 callers
- Never share personal or financial details with an unexpected caller, however urgent they sound.
- Block the number using your phone’s built-in call-blocking feature or a reputable call-screening app.
- Look up the number with a trusted reverse phone lookup before returning any call.
- Report it to the FTC at reportfraud.ftc.gov and register at DoNotCall.gov.
Nearby & Related Area Codes in California
Area code 650 sits at the center of the San Francisco Bay Area codes:
- 415 & 628 — San Francisco and Marin County to the north (see our 415 area code guide)
- 408 & 669 — San Jose and Silicon Valley to the south (see our 408 area code guide)
- 510 & 341 — Oakland and the East Bay
- 831 — Santa Cruz and Monterey
Explore more codes across the state on our California area codes hub, or browse every prefix in our US area codes directory.
↑ See the complete list of All US Area Codes by State – every area code across all 50 states in one directory.
Explore Neighboring States
Researching area codes just across the state line? Start with these codes in the states that border California:
Frequently Asked Questions About Area Code 650
Where is the 650 area code located?
Area code 650 covers the San Francisco Peninsula in San Mateo County, California, including San Mateo, Redwood City, Palo Alto, and Daly City. It operates on Pacific Time.
Is 650 a landline or cell phone area code?
Both. Area code 650 serves landlines, mobile phones, and VoIP numbers throughout the Peninsula.
Does 650 have an overlay area code?
No. 650 remains a single area code without an overlay, though 10-digit dialing is now standard statewide.
Should I answer a call from an unknown 650 number?
If you are not expecting the call, let it go to voicemail. Legitimate callers leave a message, while spoofed or robocall numbers usually will not. Verify any unfamiliar number with a reverse lookup before calling back.
Related 650 Guides
- Is a 650 call safe? Read Is area code 650 a scam? Spam & safety guide.
- Worried about spam or robocalls? Browse our Scam Alerts directory.