Phone Number Validator

Validate international phone numbers with libphonenumber — real per-region rules, line type, and E.164 / national / international formats.

Phone Number

Default region

How phone number validation works

Phone numbers follow country-specific rules defined by the ITU-T E.164 standard. This validator uses libphonenumber— Google’s phone-number library (the same rules behind Android) — so it validates 200+ regions with real length and prefix rules, detects the line type (mobile, fixed line, toll-free, VoIP, …), and formats the number three ways: E.164 (the canonical international form, e.g. +14155552671), national, and international. Numbers typed without a +code are interpreted using the selected default region. Your number stays on your device — it is never uploaded, and (unlike most inputs on this site) it is deliberately kept out of the shareable page URL.

Built and maintained by Meet Shah · Last updated 24 July 2026

What this tool is used for

Checking whether a number is well formed for its country before storing it.
Detecting which country a number belongs to from its prefix.
Normalising a number to E.164 for an API.
Validating a list of numbers before an import.
Distinguishing a malformed number from an unreachable one.

Frequently Asked Questions

What does validation actually confirm?: That the number is possible and correctly formed for its country — right length, valid prefix, plausible number type. It cannot confirm the line exists or that anyone answers it; that requires an actual carrier lookup, which no client-side tool can do.
What is E.164 format?: The international standard: a plus sign, the country code, then the national number with no spaces or punctuation, maximum 15 digits — `+442071838750`. It is the only format that is unambiguous worldwide, which is why it is what you store rather than what you display.
Why does a number need a default country?: Because a national-format number is meaningless without one. `020 7183 8750` is a London number in the UK and nothing anywhere else, and the leading zero is a national trunk prefix that is dropped in E.164 — which is the single most common phone-formatting mistake.
What does the number type tell me?: Whether it is mobile, fixed line, toll-free, premium rate or VoIP, inferred from the prefix. It matters practically: you cannot SMS most fixed lines, and premium-rate numbers cost the caller, so a form accepting one where it expected the other creates real problems.
Can I validate with a regular expression?: Not reliably. Numbering plans differ by country, change over time, and have exceptions — a regex that appears to work is usually rejecting valid numbers from countries nobody tested. That is precisely why libphonenumber exists and is the size it is.

Common errors and gotchas

Reading well-formed as reachable, which only a call or a message establishes.
Assuming the country from the user's locale rather than the number itself.
Dropping a leading zero that belongs to the national format but not after the country code.
Accepting a number that is valid in format but assigned to a range that cannot receive messages.
Validating length against one rule, when it varies by country and by number type.