E.164 Format Converter
Convert any phone number to E.164 format — the ITU-T standard required by WhatsApp, Twilio, Stripe, and most CRMs. Paste a single number or a full list, and get E.164, international (E.123), national, and RFC 3966 (tel:) formats with one-click copy. No signup, no upload — everything runs in your browser using libphonenumber-js.
Last updated: 2026-10-27
E.164 Format Converter
Default country (used when the number has no “+”): change it in the country selector at the top of the page.
How to Convert a Phone Number to E.164
- Pick the default country in the country selector — used when the input number has no + prefix.
- Paste a phone number into the converter (any format: dashes, parentheses, spaces, dots).
- Read the four output formats: E.164, international, national, and RFC 3966 (tel:).
- Click the copy button next to the format you need — E.164 for APIs, RFC 3966 for click-to-call links.
- Switch to bulk paste mode to convert an entire list of numbers at once and copy them as a newline-separated batch.
When You Need E.164 Format
- Sending WhatsApp click-to-chat links (wa.me) — WhatsApp requires E.164 format.
- Calling Twilio, Vonage, MessageBird, or Plivo APIs — all SMS and voice APIs mandate E.164.
- Storing phone numbers in databases that serve a multi-country user base.
- Importing contact lists into Salesforce, HubSpot, or any CRM that normalizes phone fields.
- Building click-to-call buttons (RFC 3966 tel: URIs work everywhere E.164 storage does).
Frequently Asked Questions
▶What is E.164 phone number format?
E.164 is the ITU-T international standard for telephone numbers. An E.164 number begins with a + sign, followed by the country code (1–3 digits) and the subscriber number, with no spaces, dashes, parentheses, or leading zeros — for example, +14155551234 (US) or +447911123456 (UK). E.164 is the canonical phone number format used by WhatsApp, Twilio, Stripe, most CRMs, and international carrier routing systems.
▶What is the maximum length of an E.164 phone number?
An E.164 phone number can be at most 15 digits, not counting the leading + sign. The country code accounts for 1 to 3 of those digits, and the remaining digits are the national subscriber number. The minimum is also defined per country, but in practice most valid numbers fall between 8 and 15 digits.
▶How do I convert a phone number to E.164 format?
Paste the number into the converter above. If the number already starts with a + and country code, the converter parses it directly. If it does not, select the country the number belongs to using the country selector in the navigation bar — the converter then prepends the correct country code, strips any local trunk prefix (for example, the leading 0 used in many European countries), and removes spaces and punctuation to produce a valid E.164 string.
▶E.164 vs international format — what is the difference?
E.164 and the international format (sometimes called E.123) carry the same information but use different presentation rules. E.164 is the strict machine-readable form: + followed by digits only, no separators (+14155551234). The international format is the human-readable presentation, with spaces between the country code, area code, and subscriber number (+1 415 555 1234). Use E.164 for storing numbers in databases or sending to APIs; use international format when displaying numbers to users.
▶What is RFC 3966 and when do I use it?
RFC 3966 defines the tel: URI scheme used for click-to-call links and softphone integrations. It looks like tel:+14155551234 and works in href attributes on web pages, in VoIP applications, and across mobile platforms. The converter outputs RFC 3966 alongside E.164 because the two formats are commonly used together — E.164 for storage and APIs, RFC 3966 for the actual click-to-call link in HTML.
▶Does WhatsApp require E.164 format?
Yes. WhatsApp click-to-chat URLs (the wa.me links) require numbers in E.164 format with the + sign omitted — for example wa.me/14155551234. The WhatsApp Business API also mandates E.164 for all phone number fields. Converting to E.164 first is the safest way to ensure your WhatsApp links open correctly across regions and carriers.
▶Can I convert a list of phone numbers to E.164 in bulk?
Yes. Switch the converter to “Bulk paste” mode and paste a list of numbers, one per line. Each line is parsed independently against the selected default country, and the converter shows a table of the original input, the resulting E.164 value, and the detected country for each row. Invalid numbers are flagged so you can clean the list before exporting. Use the “Copy all E.164” button to copy the converted list to your clipboard.
▶Is the E.164 converter free to use?
Yes. The NumSwift E.164 converter is completely free, requires no signup, and runs entirely in your browser using the libphonenumber-js library. There are no usage limits, no API quotas, and no data ever leaves your device — making it suitable for use with sensitive customer phone lists.