United States (+1 / 001): 10 digits
Locals write (415) 555-0123. An API wants +14155550123. Paste any United States number below to see it normalised, validated, and identified.
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How United States numbers are written
- Country calling code
- +1
- Dialled from abroad
- 001 (011 1 from the US and Canada)
- ISO country code
- US
- National number length
- 10 digits
- Trunk prefix
- 1 (dropped in E.164)
- Written locally
- (415) 555-0123
- E.164 format
- +14155550123
What +1 means
+1 is the country calling code for United States. The same code is written 001 when you dial out from most of Europe, Africa and Asia, and 011 1 from the US and Canada. All three reach the same place: only the exit code in front of it changes. Whichever one you use, the national trunk 1 is dropped once the country code is in front.
Mobile numbers
Mobile and landline share the same numbering plan, so line type needs a carrier lookup rather than a prefix rule.
Converting to E.164
Take the number as written locally ((415) 555-0123), drop the leading 1, then prefix +1. The result is +14155550123: no spaces, no dashes, no parentheses. Store that, and format for display only when you show it to a human.
Why not do it with a regex
A pattern that matches United States numbers today breaks the moment a new mobile range is allocated, and it cannot tell you whether the number is actually assigned. The tool above runs the same numbering-plan engine as our phone validation API, so it also reports line type and region rather than just shape.
United States area codes by city
- New York
- 212, 646, 917
- Los Angeles
- 213, 310, 323
- Chicago
- 312, 773
- Houston
- 713, 281
- San Francisco
- 415
- Miami
- 305, 786
A US number does not tell you whether it is a mobile
The United States, Canada, Mexico and Chile are the only countries on this site where the numbering plan does not separate mobile from landline: the same area code issues both, so no prefix rule can tell them apart. Anyone claiming to detect a US mobile from the digits alone is guessing. It takes a live network lookup — which is exactly what a carrier or HLR query does.
United States phone numbers, answered
How many digits is a US phone number?
Ten: a three-digit area code, a three-digit exchange, and four more. With the +1 country code that is eleven, which is why US numbers are often written 1-212-555-0123.
Can you tell if a US number is a cell phone?
Not from the number. The US shares the North American Numbering Plan with Canada, and both issue mobile and landline numbers out of the same area codes. The only reliable answer comes from querying the network the number currently sits on — portability means even the original carrier is no guide.
What is a 555 number?
555-0100 through 555-0199 are reserved for fiction, which is why they appear in films. They are safe to use as examples and are never assigned to a real subscriber. The rest of the 555 range is not reserved.
That is how a United States number is written. Whether a whole list is worth dialling is the free call list cleaner, or check one number on the spam phone checker.