California · Pacific Time
840 Area Code
Area code 840 is in California, serving western San Bernardino County and the Pomona Valley of eastern Los Angeles County. It is in the Pacific Time zone. It shares its territory with overlay code 909, so 10-digit dialing is required.
Last updated October 1, 2026 · Source: NANPA
Where is the 840 area code?
840 is a California area code covering western San Bernardino County and the Pomona Valley of eastern Los Angeles County. In the wider directory it sits in the West region.
Cities in the 840 area code
- San Bernardino
- Fontana
- Ontario
- Rancho Cucamonga
- Pomona
- Chino
- Upland
- Rialto
- Redlands
- Chino Hills
- Colton
- Highland
- Diamond Bar
- Yucaipa
Counties served by 840
San Bernardino County and Los Angeles County.
840 overlay codes and dialing
The 840 territory is covered by an overlay of 2 area codes: 840, 909. All of them serve the same geographic area, and the original code is 909. Because more than one code covers the same ground, 10-digit dialing is mandatory — you must dial the area code for every local call. New phone lines may be assigned any of these codes.
History of the 840 area code
840 went into service on February 23, 2021 as an overlay of 909, relieving number exhaustion in the San Bernardino area. Rather than splitting the region, the overlay lets existing customers keep their numbers while new lines draw from the added code. Learn more in our overlay guide.
Is 840 a scam or spam risk?
840 is a legitimate geographic area code, not a premium or toll line, so a call from it costs you nothing extra. That said, scammers frequently spoof real local area codes to look familiar on caller ID. A genuine 840 number on your screen is no guarantee the caller is in San Bernardino, CA or trustworthy. See spam & scam-risk area codes for how spoofing works and how to respond.
Other California area codes
Explore more
See every code in California, compare codes across the West region, or view all Pacific Time codes. You can also browse the 8XX block or the complete numeric list of US area codes.
New to how this all works? Start with how area codes work, then read up on overlays, 10-digit dialing, and spam & scam-risk codes. To check another number, use the area code lookup tool.
Quick answers
840 area code FAQ
Where is the 840 area code?
The 840 area code is in California, covering western San Bernardino County and the Pomona Valley of eastern Los Angeles County, in the West region.
What cities are in the 840 area code?
Cities in the 840 area code include San Bernardino, Fontana, Ontario, Rancho Cucamonga, Pomona, Chino, Upland, Rialto, Redlands and Chino Hills.
What time zone is 840 in?
840 is in the Pacific Time zone.
What is the overlay for the 840 area code?
840 shares its territory with 909. Both codes (840, 909) serve the same area, so 10-digit dialing is required for every call.
When did the 840 area code start?
840 went into service on February 23, 2021 as an overlay of 909.
Do I have to dial 10 digits for 840?
Yes. Because 840 is an overlay area, you must dial the full 10-digit number (area code + 7 digits) for every call.
Is 840 a toll-free or premium code?
No. 840 is a standard geographic area code, so calling it costs the same as any local or long-distance call on your plan. Toll-free calls use 800, 888, 877, 866, 855, 844 or 833.