Area codes in Rancho Cucamonga, California

Rancho Cucamonga, California uses 2 area codes — 909 and 840. The main Rancho Cucamonga area code is 909.

Area codes serving Rancho Cucamonga

Phone numbers in Rancho Cucamonga are written as ten digits — for example (909) 555-0190 — and fall in the Pacific Time zone.

How Rancho Cucamonga came to have 2 area codes

The original Rancho Cucamonga area code is 909, in service since 1992. As the area ran low on available numbers, an overlay code was added over the same region for new phone lines: 840 (2021). Existing numbers kept their original code — an overlay never forces anyone to change their number — which is why Rancho Cucamonga now uses all 2 codes and every local call is dialed with ten digits.

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Frequently asked questions

What is the area code for Rancho Cucamonga?

The main area code for Rancho Cucamonga, California is 909. Rancho Cucamonga is now served by 2 area codes in total: 909, 840.

How many area codes does Rancho Cucamonga have?

Rancho Cucamonga has 2 area codes: 909, 840.

Why does Rancho Cucamonga have more than one area code?

As Rancho Cucamonga used up the numbers available in its original area code (909, in service since 1992), additional "overlay" codes were added over the same area so new phone numbers could keep being assigned.

How do you dial a Rancho Cucamonga number?

Dial all 10 digits — the area code (909 or 840) followed by the 7-digit local number. From abroad, dial +1, then the area code and number.

Sourced from the official NANPA (North American Numbering Plan Administrator) numbering database, current as of August 2, 2026. Refreshed monthly.