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The 840 area code covers the same area as 909, including Ontario, San Bernardino and 21 more places in California.

Area code 840 is in California, on Pacific Time. In the 840 area, phone numbers are given out most in San Bernardino County, then Los Angeles and Riverside counties. It has been in service since February 23, 2021. 909 covers the same area, so two neighbours can have different area codes.

Where
4 counties in California, mostly San Bernardino County, Los Angeles County and Riverside County
Time zone
Pacific Time
In service since
February 23, 2021
Shares its area with
909 (since 1992)
Prefixes in use
126
How to dial
Local calls need 1, then the area code, then the number: 1-840-555-0142.

Find out who called you from an 840 number.

Enter the full 10-digit number to see who it is listed to, the city and state on the listing, and whether it is a mobile, landline or VoIP line. It is the same free check as our who called me lookup. To see only the caller ID name on the number, use our free CNAM lookup.

Works for US & Canada numbers. Enter a 10-digit number, e.g. (415) 555-0132.

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Pomona holds 13% of the phone prefixes in area code 840.

A prefix is the three digits after the area code, and NANPA assigns each one to a town. Counting the 126 prefixes in use shows where 840 numbers are actually given out.

  • Pomona16 prefixes, 13%
  • San Bernardino14 prefixes, 11%
  • Fontana12 prefixes, 10%
  • Chino8 prefixes, 6%
  • Claremont8 prefixes, 6%
  • Ontario7 prefixes, 6%
  • Upland7 prefixes, 6%
  • Colton6 prefixes, 5%
One dot per US area code; 840 is the ringed one.

Also served: Redlands, Rialto, Diamond Bar and Highland and 11 smaller places.

Each prefix, or block of 1,000 numbers inside it, is also handed to a carrier. A number keeps its digits when its owner switches carrier, so the prefix no longer tells you who carries it today. Our free carrier lookup shows which carrier an 840 number is on now.

840 started in 2021 as an overlay on 909, and its ground has not changed since.

  1. 2021

    840 starts on February 23, 2021, as an overlay on 909: new numbers on the same ground.

An 840 number on your screen can still be a scam, because caller ID is easy to fake.

  1. Let an unknown call go to voicemail. A real caller leaves a message; a robocaller usually does not.
  2. Look the number up with the box above before you call back, because calling back tells a robocaller your line is live.
  3. Hang up on anyone who wants gift cards, crypto or a wire transfer, or asks you to read out a code that was just texted to you.
  4. Report unwanted robocalls at reportfraud.ftc.gov, or paste a suspicious message into our free scam checker.

The area codes closest to 840 are 951, 714 and 626.

This list measures the distance between the centres of each area, across state lines, and shows codes that share one area together.

951Riverside, CA714 / 657Anaheim, CA626Alhambra, CA949Irvine, CA562Long Beach, CA213 / 323 / 738Los Angeles, CA

California has 40 other area codes.

209Stockton213Los Angeles279Sacramento310Santa Monica323Los Angeles341Oakland350Stockton357Kingsburg369Santa Rosa408San Jose415San Francisco424Beverly Hills442Victorville510Oakland530Chico559Fresno562Long Beach619San Diego626Alhambra628San Francisco650Palo Alto657Anaheim661Bakersfield669San Jose707Santa Rosa714Anaheim738Los Angeles747Burbank760Palm Springs805Santa Barbara818Van Nuys820Camarillo831Salinas837Redding858San Diego909Ontario916Sacramento925Walnut Creek949Irvine951Riverside

Browse every US area code

These are the questions people ask most about area code 840.

Where is area code 840?

840 covers Ontario, San Bernardino, Fontana and Upland and 19 more places in California. In the 840 area, phone numbers are given out most in San Bernardino County, then Los Angeles and Riverside counties.

What state is area code 840 in?

California. 840 is a California area code on Pacific Time.

What cities use area code 840?

The places holding the most 840 prefixes are Ontario, San Bernardino, Fontana, Upland, Chino, Pomona, Claremont and Colton, out of 23 places in all. The count comes from NANPA's prefix assignments as of October 1, 2026.

What time zone is area code 840 in?

840 is on Pacific Time.

When did area code 840 start?

840 went into service on February 23, 2021, as an overlay on 909: new numbers for the same area.

Is 840 the same area as 909?

Yes. 909 (since 1992) covers the same ground as 840. Nobody's number changed when it was added; new lines simply get whichever code has numbers left, so two neighbours can have different codes.

How do I dial an 840 number?

Local calls need 1, then the area code, then the number: 1-840-555-0142.

Is 840 a toll-free number?

No. 840 is a regular area code for Ontario and San Bernardino in California, not a toll-free one. The toll-free codes in North America are 800, 833, 844, 855, 866, 877 and 888.

What area codes are near 840?

The closest are 951 (Riverside, California), 714/657 (Anaheim, California), 626 (Alhambra, California) and 949 (Irvine, California), measured between the centres of each area.

Who called me from an 840 number?

Enter the full 10-digit number in the lookup above. It returns the listed owner where there is a public record, where the number is registered, and whether it is a mobile, a landline or a VoIP line.

Is area code 840 a scam?

840 is a real California area code, so the code itself is not a warning sign. Scam callers fake local-looking numbers on purpose, so judge the call by what the caller asks for, and look the number up before calling back.

Source: NANPA, the North American Numbering Plan Administrator: its area code database and prefix assignments, as of October 1, 2026.