Phone Number Formats and Country Codes Explained
A wrong format is one of the most common reasons a code never arrives or a form says “invalid phone number”. Every number has two parts: the country code and the national number.
By the editorial team · Updated · 4 min read · What changed- Type +, the country code and the number without the leading zero.
- With a country picker, type only the national number.
- A duplicated country code is the most common “invalid number” cause.
A wrong format is one of the most common reasons a code never arrives or a form says “invalid phone number”. Every international number has two parts: the country code and the national number, written in the E.164 format. This guide gives the one rule that works in every form, the formats for common countries, and the mistakes that trip people up.
For: Anyone entering a number in a sign-up form, especially from another country.
Covers: Country codes, number lengths and common format mistakes.
Not covered: Local dialing rules for calls.
Key terms: E.164 format, Country code
How to Enter a Phone Number in Any Form
Use the international format: a plus sign, the country code, then the national number without a leading zero. If the form has a country picker, choose the country there and type only the national number. Leave out spaces, dashes and brackets.
- 01Start with a plus sign and the country code: +1, +44, +91.
- 02Add the rest of the number without the leading zero that local numbers often start with.
- 03If the form has a country picker, choose the country there and type only the national number.
- 04Leave out spaces, brackets and dashes if the form rejects them.
Country Codes and Phone Number Lengths
Every country has its own dialing code and number length, and forms reject numbers that are too short or too long. Check the code and the digit count for your country below before you paste a number into a sign-up form.
| Country | Code | Digits after the code | Example format |
|---|---|---|---|
| USA | +1 | 10 | +1 646 555 0117 |
| Canada | +1 | 10 | +1 416 555 0142 |
| United Kingdom | +44 | 10 | +44 7700 900271 |
| India | +91 | 10 | +91 98765 43210 |
| Netherlands | +31 | 9 | +31 6 12345678 |
| Germany | +49 | 10–11 | +49 151 23456789 |
| Brazil | +55 | 11 | +55 11 91234 5678 |
The full list with mobile prefixes is on the Countries page.
What Is the Country Code for USA Phone Numbers?
It’s +1, shared with Canada and several Caribbean countries. A US number has 10 digits after the code: a 3-digit area code and a 7-digit number. In a form with a country picker, choose United States and type the 10 digits.
Common Phone Number Format Mistakes
Most “invalid phone number” errors come from three mistakes: the country code typed twice, a leading zero kept after the code, or no country code at all. Each one has a quick fix, shown in the table below.
| Mistake | What happens | Fix |
|---|---|---|
| Country code typed twice (+1 picker, then +1 in the field) | “Invalid number” | Type only the national number |
| Leading zero kept (+44 07700…) | Invalid or wrong number | Drop the zero |
| No country code | The app treats it as a number in your own country | Add + and the code |
| Wrong country in the picker | The code goes to a different number | Re-select the country |
Phone Number Format FAQ
How do I write a US phone number?+
Internationally: +1, then the 10-digit number, for example +1 646 555 0117. Inside the US people write (646) 555-0117, but sign-up forms usually want only the digits. Drop the brackets, spaces and dashes, and don’t add a 0 or 1 in front if the form already shows +1. A US number always has 10 digits after the country code.
What is the Brazilian phone number format?+
+55, a 2-digit area code, then a 9-digit mobile number that starts with 9. For example +55 11 91234 5678. With a country picker, choose Brazil and type the 11 digits. Without one, type the full number starting with +55.
Why does the form say “invalid phone number”?+
Usually the country code is duplicated, a leading zero was kept, or the app doesn’t accept numbers from that country. Fix the format first, then try another country. Remove spaces and dashes, check that the number has the right length for its country, and choose the country in the picker instead of typing the code twice.
Do I need the plus sign?+
If the form has no country picker, yes. Without it, the app may read the country code as part of a local number. In forms with a country picker, the plus and country code are added for you, so leave them out.
Can I tell the country from the number?+
Yes, from the country code. Numbers starting with +1 can be from the US, Canada or some Caribbean countries; the area code tells them apart. A full list of codes and number lengths is on the Countries page. The page lists every code.
- E.164 numbers have at most 15 digits, including the country code.
- US and Canada numbers have 10 digits after +1; UK mobile numbers have 10 digits after +44.
- Source: ITU-T E.164 and national numbering plans.
Formats follow the ITU-T E.164 numbering plan and each country’s mobile number length. Examples use fictional numbers.
When this guide won’t help- Some forms add the country code for you: don’t type it twice.
- Some apps refuse numbers from certain countries even in the right format.
General information only. Apps change their checks often; follow each app’s terms and never use a free number for banking, payments or government services.