What is E.164 phone number format?
E.164 is the international standard for phone numbers: a + then country code and number, max 15 digits. Learn the format and validate a number free.
E.164 is the ITU standard for how a phone number should be written for international use: a leading +, the country calling code, and the subscriber number, with no spaces or punctuation, up to 15 digits total. Example: +14155552671.
The structure
An E.164 number is + [country code] [national number]. The + means "international prefix"; the country code (1 for the US/Canada, 44 for the UK, 380 for Ukraine) routes to a country; the rest is the national number. Total digits after the + never exceed 15.
Why APIs require it
E.164 is unambiguous — there is exactly one way to write a given number. That is why SMS, WhatsApp, and verification APIs (including ours) expect numbers in E.164: no guessing about national prefixes, trunk zeros, or formatting.
Common mistakes
Leaving the leading 0 of a national number in place after the country code, adding it without removing the international 00 prefix, or including spaces and dashes. A validator normalizes all of these to a single canonical E.164 string.
Try it now — free, no signup
Use the phone validator in your browser. Then, when you need it at scale with an API key and higher limits, grab the full Eveses API.