What is the correct format for a US fax number?

A standard US fax number is written as (212) 555-1234 for domestic use, or +1 212 555 1234 for international use. The country code for the US and Canada is +1. All formats are interchangeable — fax machines and online services strip punctuation automatically.

What is the E.164 format for fax numbers?

E.164 is the international ITU standard for phone and fax numbers. Format: + [country code] [area code] [local number], with no spaces or special characters. Example: +12125551234 (US) or +442071234567 (UK). Learn more about [international faxing](/blog/complete-guide-international-faxing/).

Do I need to include the country code when sending a fax domestically?

No. For domestic faxes within the US or Canada, you can write just the 10-digit number: (area code) + local number. The country code (+1) is only required for international senders trying to reach you.

What prefix should I use for a fax number on a business card?

Both "F:" and "Fax:" are correct and widely recognized. "F:" is more modern and saves space; "Fax:" is traditional and unmistakable for older audiences. Pick one and use it consistently.

Can I use dots or dashes in a fax number?

Yes. All three separators — dashes (212-555-1234), dots (212.555.1234), and parentheses ((212) 555-1234) — are valid for display purposes. Online fax services like mFax.to ignore all non-digit characters (except the + sign) when routing the transmission.

Fax Number Formats: How to Write and Use Them Correctly

Parentheses, dashes, dots, or plus signs — which fax number format is actually correct? This guide covers every format from local US numbers to international E.164 notation, with examples for business cards, email signatures, and online fax services.

Frequently Asked Questions

What is the correct format for a US fax number?: A standard US fax number is written as (212) 555-1234 for domestic use, or +1 212 555 1234 for international use. The country code for the US and Canada is +1. All formats are interchangeable — fax machines and online services strip punctuation automatically.
What is the E.164 format for fax numbers?: E.164 is the international ITU standard for phone and fax numbers. Format: + [country code] [area code] [local number], with no spaces or special characters. Example: +12125551234 (US) or +442071234567 (UK). Learn more about [international faxing](/blog/complete-guide-international-faxing/).
Do I need to include the country code when sending a fax domestically?: No. For domestic faxes within the US or Canada, you can write just the 10-digit number: (area code) + local number. The country code (+1) is only required for international senders trying to reach you.
What prefix should I use for a fax number on a business card?: Both "F:" and "Fax:" are correct and widely recognized. "F:" is more modern and saves space; "Fax:" is traditional and unmistakable for older audiences. Pick one and use it consistently.
Can I use dots or dashes in a fax number?: Yes. All three separators — dashes (212-555-1234), dots (212.555.1234), and parentheses ((212) 555-1234) — are valid for display purposes. Online fax services like mFax.to ignore all non-digit characters (except the + sign) when routing the transmission.