Area Code Lookup
What Area Code Is Ontario?
2 area codes serve Ontario · California
Ontario is served by area codes 840, 909. It is located in California.
Area Codes Serving Ontario
Frequently Asked Questions
What area code is Ontario?
Ontario is served by area codes 840, 909. It is located in California.
Why does Ontario have multiple area codes?
As demand for phone numbers increased, NANPA added area codes through splits (dividing the region) or overlays (layering a new code over the same geography). Ontario now has 2 area codes — 840 and 909 — covering the same or overlapping areas.
How do I call Ontario from outside the US?
To call Ontario from abroad, dial +1 followed by the area code and 7-digit local number (e.g. +1-840-XXX-XXXX). The +1 is the country code for all NANPA countries.