Phone number formatter & E.164 validator

What E.164 is and why it matters

E.164 is the ITU recommendation that defines the international public telephone numbering plan. It says that every phone number in the world can be written as a country calling code of one to three digits followed by a national significant number, with a maximum of 15 digits overall. Written with a leading plus sign and nothing else — no spaces, dashes, brackets or trunk 0 — the number is unambiguous: +14155550123 can only mean one line, from any country.

That is why sign-up forms, SMS gateways, CRMs and verification APIs store numbers in E.164. When two systems exchange a number in any other format, something eventually goes wrong: a trunk 0 kept after the country code, a country code typed twice, or a local number read against the wrong country. Many “invalid phone number” errors in sign-up flows come down to one of these.

The three formats the tool shows

• E.164 — +, country code, national number, no spaces. Use it for APIs, databases and single-box forms.
• International — the same digits grouped for reading, e.g. +44 7700 900123. Use it on business cards and in email signatures.
• National — how people in that country write it, usually with the trunk 0, e.g. 07700 900123. Use it only for local audiences.

The tool also produces a tel: link you can drop into a web page so the number is tappable on phones.

Valid, possible, or neither

The formatter checks the digits against the country's numbering plan. Valid means the length and the leading digits match a range the country has allocated. Right length but not a valid range usually means a typo in the first digits or the wrong country picked. Not valid means the length is wrong for that country. None of these tell you whether the number is currently active or which network it is on — that information lives with the mobile operators and is only available through a live lookup such as an HLR lookup.

How to use it

1. Pick the country the number is from. It is only used when the number doesn't already start with + or 00.
2. Type or paste the number in whatever form you have it.
3. Copy the format you need with the copy button next to it.

Need the dial code or the usual mobile layout for a country first? The country calling codes table lists all of them. Wondering whether an app will treat a number as mobile or VoIP? See the VoIP vs mobile checker.

The tool is built on libphonenumber-js, an open-source port of Google's libphonenumber, the numbering-plan library used by Android and many messaging apps. Numbering plans change a few times a year, so a newly opened range may briefly show as not valid.