Area codes in Naperville, Illinois
Naperville, Illinois uses 2 area codes — 630 and 331. The main Naperville area code is 630.
Area codes serving Naperville
Phone numbers in Naperville are written as ten digits — for example (630) 555-0190 — and fall in the Central Time zone.
How Naperville came to have 2 area codes
The original Naperville area code is 630, in service since 1996. As the area ran low on available numbers, an overlay code was added over the same region for new phone lines: 331 (2007). Existing numbers kept their original code — an overlay never forces anyone to change their number — which is why Naperville 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 Naperville?
The main area code for Naperville, Illinois is 630. Naperville is now served by 2 area codes in total: 630, 331.
How many area codes does Naperville have?
Naperville has 2 area codes: 630, 331.
Why does Naperville have more than one area code?
As Naperville used up the numbers available in its original area code (630, in service since 1996), additional "overlay" codes were added over the same area so new phone numbers could keep being assigned.
How do you dial a Naperville number?
Dial all 10 digits — the area code (630 or 331) 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.