What Is E.164 Phone Number Format?
Updated 2026-07-04 · By the MakeToolz team
Quick answer: E.164 is the international standard format for phone numbers. It is a +, then the country code, then the national number, with no spaces, dashes, or brackets, and up to 15 digits total. Example: +14155551234. You can validate and convert numbers to E.164 with our free Phone Number Validator.
If an app has ever rejected your phone number or a text failed to send, E.164 is usually the reason. The format exists so any system anywhere can read a number the same way. Here is what each part means, why so many services demand it, and how to convert a local number in a few seconds.
The format, broken down
Take +14155551234 and split it into three parts:
- + signals international format. It replaces the "00" or "011" dialing prefix you would otherwise punch in.
- 1 is the country code. 1 is US and Canada, 44 is the UK, 91 is India, and so on.
- 4155551234 is the national subscriber number.
The whole thing is at most 15 digits after the plus sign, with no other characters allowed. That hard limit is part of the standard, which keeps every number the same predictable shape.
Why apps and APIs require E.164
SMS gateways like Twilio, WhatsApp Business, CRMs, and payment systems all standardize on E.164 because it is globally unambiguous. One number, one format, no guessing the country. A number written as "0791 112 3456" means nothing without knowing where it is from, but +447911123456 is precise anywhere in the world.
Storing numbers this way also saves engineers from a mess of edge cases. They do not have to parse brackets, dots, or local shorthand. The number arrives clean, so it can be dialed, texted, or matched against a database with no cleanup.
How to convert a local number to E.164
- Start with
+and the country code for that number. - Drop the leading 0 from the national number. That 0 is a trunk prefix used only for domestic dialing, and the country code replaces it.
- Remove all spaces, dashes, and brackets so only digits remain.
Examples make it clear:
- US: (415) 555-1234 becomes
+14155551234 - UK: 07911 123456 becomes
+447911123456(drop the 0) - India: 098765 43210 becomes
+919876543210(drop the 0)
Not sure a number is right? Paste it, or a whole list, into the Phone Number Validator. It checks the expected length for each country and outputs a clean E.164 version you can copy.
Common mistakes to avoid
- Keeping the leading 0 after the country code, like
+4407911.... That extra zero is wrong and will break the number. - Leaving in spaces or dashes. E.164 is digits only after the plus sign.
- Forgetting the country code. It is required, even when the number is only used locally inside an app.
Most rejected numbers fall into one of these three traps. Fixing them is usually the whole job.
People Also Ask
What does E.164 stand for?
It is the name of the ITU-T recommendation that defines the international public telephone numbering plan. "E.164" is simply the standard's catalog number, not an acronym for anything.
Does E.164 include the plus sign?
Yes. The leading + is part of the format. It tells systems that a country code follows. Some databases store the digits without the plus and add it back on display, but the true E.164 string includes it.
What is the maximum length of an E.164 number?
15 digits after the plus sign, and that count includes the country code. Most real numbers are shorter, but no valid E.164 number goes past 15 digits.
How do I format a whole list of numbers at once?
Paste them one per line into the Phone Number Validator. It validates each one and gives you a copy-ready E.164 list, so you do not have to convert them by hand.
What is the difference between E.164 and a national format?
National format is how you write a number for people in the same country, often with a leading 0, spaces, and brackets, like (415) 555-1234. E.164 is the international machine-readable version with a plus and country code and no formatting. Apps want E.164; humans usually read national format.
Why does my number get rejected when I sign up for services?
Almost always because it is not in E.164. The two usual culprits are a missing country code or a leftover leading 0. Add the + and country code, drop the 0, strip spaces and dashes, and the number will pass.
Do I always drop the leading zero?
In most countries, yes. The leading 0 is a domestic trunk prefix and the country code replaces it. A few numbering plans handle this differently, so when in doubt, run the number through a validator that knows each country's rules.
Is E.164 the same as international dialing with 00 or 011?
They serve the same goal but differ in the prefix. When you dial abroad you press 00 or 011 before the country code. E.164 uses a single + in its place, which phones translate to the correct exit code automatically. So +44 and dialing 011 44 reach the same place.
Working with a batch of numbers? Run them through the Phone Number Validator to check each one and get a clean E.164 list in seconds.