WhatsApp Phone Number Format: How to Write Numbers in E.164
The WhatsApp phone number format is E.164, the international numbering standard defined by the ITU (International Telecommunication Union). A number in this format has a + sign, the country code and the national number, with no spaces, leading zeros or dialing prefixes, and no more than 15 digits in total. A US mobile number looks like this: +14155550132. It is the format that the WhatsApp API and validation tools read without ambiguity.
How is a number in WhatsApp phone number format built?
| Part | Example (US) | Rule |
|---|---|---|
| + sign | + | Marks an international number |
| Country code | 1 | 1 to 3 digits, different for each country |
| National number | 4155550132 | Area or mobile prefix plus subscriber number, without the domestic dialing prefix |
In links such as wa.me, the same number is written without the +: 14155550132.
From local format to E.164: examples from five countries
| Country | How it appears locally | In E.164 | What changed |
|---|---|---|---|
| United States | (415) 555-0132 | +14155550132 | Country code 1 added, symbols removed |
| United Kingdom | 07911 123456 | +447911123456 | Leading 0 removed, country code 44 added |
| India | 098765 43210 | +919876543210 | Leading 0 removed, country code 91 added |
| Mexico | 55 1234 5678 | +525512345678 | Country code 52 added |
| Brazil | (11) 98765-4321 | +5511987654321 | Country code 55 added, symbols removed |
The general rule: remove the national dialing prefix (usually 0) and put the country code in front.
A country-specific wrinkle. Numbering plans change. Brazil, for example, added a ninth digit to mobile numbers, so old lists still hold 8-digit mobile numbers such as 11 8765-4321 that must become +5511987654321. If a country on your list has changed its numbering plan, check that country's regulator before bulk-fixing.
How to format a whole list to the WhatsApp phone number format
- Keep only the digits. Remove spaces, brackets, dashes, dots and any existing +.
- Remove the national dialing prefix from the start of each number (the 0 in the UK or India, for example).
- Add the country code when it is missing. On a single-country list it is the same for every row. On an international list, use the country column from your sign-up form.
- Apply country-specific fixes, such as the Brazilian ninth digit.
- Check the length. E.164 allows up to 15 digits after the +. A quick pattern test is the regular expression
^\+[1-9]\d{6,14}$, which accepts a + followed by a first digit from 1 to 9 and up to 15 digits in total. - Remove duplicates only afterwards. Standardize first so you catch the same number written in different ways. The remaining cleaning steps are in the contact list cleaning checklist and in contact list errors.
Watch out for Excel. When you open a CSV, Excel can turn 14155550132 into 1.41556E+10 and drop the final digits for good. Import the phone column as text, never as a number.
If the list is large or comes from several sources, a validation tool can standardize and check in one pass. VeriFlow, for example, takes the list as it is and returns the numbers already formatted.
Frequently asked questions
Does WhatsApp accept numbers with the leading 0 used for domestic dialing? No. The 0 is a national dialing prefix and is not part of the international number.
Do I need the + sign in my file? It depends on the tool. E.164 is written with a +, but many systems, such as wa.me links, ask for digits only, with no leading zeros, brackets or dashes (WhatsApp: how to use click to chat). What matters is that the country code is there.
Does a correct format mean the number has WhatsApp? No. Formatting makes the number readable by systems. Knowing whether it has WhatsApp takes a separate check, explained in how to validate WhatsApp numbers.
Can I guess a missing country code? Only if you know every number on the list belongs to one country. On a mixed list, use the country the person selected at sign-up, because the country can't be read from the number alone.
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Frequently asked questions
Does WhatsApp accept numbers with the leading 0 used for domestic dialing?
No. The 0 is a national dialing prefix and is not part of the international number.
Do I need the + sign in my file?
It depends on the tool. E.164 is written with a +, but many systems, such as wa.me links, ask for digits only, with no leading zeros, brackets or dashes (WhatsApp: how to use click to chat). What matters is that the country code is there.
Does a correct format mean the number has WhatsApp?
No. Formatting makes the number readable by systems. Knowing whether it has WhatsApp takes a separate check, explained in how to validate WhatsApp numbers.
Can I guess a missing country code?
Only if you know every number on the list belongs to one country. On a mixed list, use the country the person selected at sign-up, because the country can't be read from the number alone.
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