E.164 phone number formatter
Every voice and SMS API expects numbers in E.164 — a plus, the country code, then the national number with nothing else. Paste a number however you have it and get the version that will actually dial.
E.164
Formats to E.164; it does not check whether the number is assigned or in service. Example for United Kingdom: +442079460958
How this is calculated
Strips formatting, removes the international access prefix (00) or the national trunk prefix if present, then prepends the country calling code. E.164 caps the result at 15 digits including the country code.
Last reviewed August 2026.
Frequently asked questions
- What is E.164 format?
- The international standard for phone numbers: a plus sign, the country calling code, then the national significant number, with no spaces, dashes or brackets. +442079460958 is E.164; 020 7946 0958 is not. Telephony APIs almost universally require it.
- Do I keep the leading zero?
- No. The leading zero is a national trunk prefix used only when dialling inside the country. In E.164 it is dropped and replaced by the country code — UK 020 7946 0958 becomes +442079460958.
- How long can an E.164 number be?
- Fifteen digits maximum, counting the country code and excluding the plus. Most countries use far fewer — a US number is 11 digits in E.164, a UK landline 12.
- Does this check whether the number is real?
- No. It converts formatting only. Whether a number is assigned and in service depends on prefix ranges that change constantly, so the tool flags unusual lengths as a hint rather than declaring a number valid or invalid.
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