Area Code 510

About Area Code 510

Area code 510 is a geographic telephone area code assigned to Oakland, California. It operates in the Pacific time zone and was first introduced in 1991. Split from 415. East Bay. Overlay 341 (2019).

Within California, area code 510 shares numbering capacity with 35 other area codes. The state's 38,965,193-person population (2023 Census Bureau estimate) is served by a combined 36 active codes, with 510 primarily responsible for the Oakland region. California's state capital is Sacramento, and its largest city is Los Angeles.

When you receive a call from a 510 number on your Caller ID, the call originated from a phone number assigned to the 510 area code — but be aware that Local Number Portability (in effect since 2003) means the caller could be physically located anywhere in the US or Canada. Area code 510 only confirms where the number was originally assigned.

Where is the 510 area code located?

Area code 510 is assigned to Oakland, California, in the Pacific time zone. The state of California uses 36 active area codes, and 510 is one of them. Calls placed from the 510 area code originate from numbers assigned by NANPA — the North American Numbering Plan Administrator — and the 510 prefix appears on Caller ID for both landline and wireless calls placed from this region.

The Pacific time zone observes Daylight Saving Time, shifting from UTC-8 to UTC-7 in summer. The local time shown above is always current, so you can quickly check whether it's a reasonable hour to call back.

What cities and counties use the 510 area code?

The 510 area code serves 11 notable cities, listed below in order of population. The largest city in the 510 territory is Oakland (440,646 residents in Alameda County).

• Oakland, CA — 440,646 residents (4.4% of 510 numbers)
• Los Angeles, CA — 3,898,747 residents (38.6% of 510 numbers)
• San Diego, CA — 1,381,611 residents (13.7% of 510 numbers)
• San Jose, CA — 971,233 residents (9.6% of 510 numbers)
• San Francisco, CA — 808,437 residents (8% of 510 numbers)
• Fresno, CA — 545,567 residents (5.4% of 510 numbers)
• Sacramento, CA — 524,943 residents (5.2% of 510 numbers)
• Long Beach, CA — 456,154 residents (4.5% of 510 numbers)
• Bakersfield, CA — 408,000 residents (4% of 510 numbers)
• Anaheim, CA — 346,824 residents (3.4% of 510 numbers)

Phone number format in area code 510

All phone numbers within area code 510 follow the standard North American 10-digit format:(510) NXX-XXXX. The NXX is the central office prefix (also called an "exchange") and XXXX is the subscriber line number. For long-distance calls within the NANP, dial 1 + 510 + NXX + XXXX. From outside North America, dial your country's international access code, then 1 (the NANP country code), then the 10-digit number.

If you need to verify whether a specific 510 number is wireless, landline, or VoIP, you can use our reverse phone lookup tool. Be aware that number portability means the area code no longer guarantees the caller's physical location — only where the number was first assigned.

History of area code 510

Split from 415. East Bay. Overlay 341 (2019).

The original 86 area codes were assigned by AT&T and Bell Labs in 1947 as part of the North American Numbering Plan. At the time, rotary-dial phones meant codes with lower digits (like 212 for NYC, 213 for LA, 312 for Chicago) were given to the largest cities because they took less time to dial. Today's area code assignments still reflect those early choices, even though touch-tone and cell phones made the original reason obsolete.

Is the 510 area code safe to answer?

Area code 510 itself is a normal geographic code with no elevated spam risk. That said, scammers can spoof any area code — including 510 — so if you don't recognize the full number, let it go to voicemail and verify the caller's identity before calling back.