By Michael Chen · Published April 28, 2026 · Updated November 13, 2026 · 8 min read
Quick answer: To fax from the US to the UK, dial 011-44 (physical fax machine) or +44 (online fax service), followed by the UK area code without its leading zero, then the local number. A London number that reads 020 7946 0958 in the UK becomes +44 20 7946 0958 from the US.
Faxing to the UK from the US trips up a lot of senders — not because the process is complicated, but because of one silent rule: drop the leading zero from the UK area code. Keep that zero in and the fax fails, with no error message that tells you why.
This guide gives you the correct format for every scenario — physical fax machine, online fax service, and email-to-fax — along with a full list of common UK area codes, the right time-zone windows for reaching UK offices, and a step-by-step walkthrough for your first transatlantic fax.
UK Country Code for Faxing: +44
The UK's country code is +44. Fax country codes are identical to international telephone country codes — both follow the ITU E.164 standard — so if you've ever called a UK number, you already know the code.
The +44 prefix replaces the leading 0 that UK numbers use domestically. You never dial both. See our complete list of fax country codes if you also need codes for other countries.
The Complete Dial Format: US to UK
The format you use depends on whether you're sending from a physical fax machine or an online fax service.
Physical Fax Machine
011 - 44 - [Area code without leading 0] - [Local number]
The 011 is the US international exit code — the signal to the US phone network that you're leaving the country. Follow it with 44 for the UK, then the area code and number.
Online Fax Service (mFax.to, eFax, etc.)
+44 [Area code without leading 0] [Local number]
Online services accept the international + prefix directly. You skip the 011 exit code entirely and enter the number in E.164 format.
Side-by-Side Examples
| UK Number (domestic) | Physical Fax Machine | Online Fax Service |
|---|---|---|
| 020 7946 0958 (London) | 011-44-20-7946-0958 | +44 20 7946 0958 |
| 0161 123 4567 (Manchester) | 011-44-161-123-4567 | +44 161 123 4567 |
| 0121 555 8800 (Birmingham) | 011-44-121-555-8800 | +44 121 555 8800 |
| 0131 999 1234 (Edinburgh) | 011-44-131-999-1234 | +44 131 999 1234 |
Spaces and hyphens don't matter
Fax machines ignore formatting characters like spaces, hyphens, and parentheses — they only dial the digits. You can enter +44-20-7946-0958, +44 20 7946 0958, or +442079460958 and the result is identical.
Common UK Area Codes (International Format)
UK area codes vary in length. Shorter area codes (like London's 20) pair with longer local numbers; longer area codes (like Manchester's 161) pair with shorter ones. The total digit count after +44 is typically 9–10 digits.
| City / Region | Domestic Code | International (after +44) | Example Full Number |
|---|---|---|---|
| London | 020 | 20 | +44 20 7946 0958 |
| Manchester | 0161 | 161 | +44 161 999 8877 |
| Birmingham | 0121 | 121 | +44 121 234 5678 |
| Edinburgh | 0131 | 131 | +44 131 556 7890 |
| Glasgow | 0141 | 141 | +44 141 221 4321 |
| Leeds | 0113 | 113 | +44 113 242 9000 |
| Bristol | 0117 | 117 | +44 117 900 0100 |
| Liverpool | 0151 | 151 | +44 151 707 1234 |
| Newcastle | 0191 | 191 | +44 191 222 5500 |
| Sheffield | 0114 | 114 | +44 114 273 5678 |
| Cardiff (Wales) | 029 | 29 | +44 29 2087 6543 |
| Belfast (N. Ireland) | 028 | 28 | +44 28 9032 1234 |
London numbers: two formats exist
Most London numbers are 11 digits domestically: 020 XXXX XXXX. But some older central London numbers still use the 0171 or 0181 format. Strip the leading 0 regardless — 0171 becomes 171, 0181 becomes 181.
Step-by-Step: How to Fax to the UK from the US
Get the complete UK fax number
Ask your recipient for their fax number in full — area code and local number. UK businesses often write it as +44 20 XXXX XXXX (already in international format) or 020 XXXX XXXX (domestic format). Either works as a starting point.
Identify and remove the leading zero
If the number starts with 0 (domestic format), remove it. That 0 is a domestic trunk prefix that only works inside the UK. It has no meaning internationally and will cause your fax to fail if left in.
Example: 020 7946 0958 → remove the 0 → area code is 20, local is 7946 0958
Build the full international number
Combine the pieces in the correct order:
- Physical fax machine: 011 + 44 + area code + local number →
011-44-20-7946-0958 - Online fax service: +44 + area code + local number →
+44 20 7946 0958
Prepare your document
Upload or scan your document. Consider including a fax cover sheet with your name, company, US fax number, and recipient details. Our free fax cover sheet generator makes one in under a minute.
If your document is a Word file or image, convert it to PDF first using our free document converter — PDF transmits most reliably across international lines.
Send and verify delivery
Send the fax and watch for a delivery confirmation. Reputable online fax services provide a delivery receipt with a timestamp. If the fax fails, double-check that no leading zero slipped through and that the total digit count matches what you'd expect (9–10 digits after +44).
The #1 Mistake: Keeping the Leading Zero
Failed faxes to the UK almost always come down to one thing: dialing +44 020 instead of +44 20.
The leading 0 is a domestic signal that only makes sense inside the UK telephone network. Outside the UK, the network doesn't know what to do with it, and the call — or fax transmission — simply fails.
Some UK numbers are written with a parenthetical zero, like +44 (0)20 7946 0958. This notation is technically correct for display purposes (it tells UK callers to use 020 domestically), but you must never dial the zero in parentheses when faxing from outside the UK.
| Format | Correct? |
|---|---|
| +44 20 7946 0958 | ✅ Correct |
| +44 020 7946 0958 | ❌ Fails — leading zero included |
| +44 (0)20 7946 0958 (dialing the 0) | ❌ Fails — same issue |
| 011-44-20-7946-0958 | ✅ Correct (physical machine) |
| 011-44-020-7946-0958 | ❌ Fails — leading zero included |
Quick check
After you enter the number, count the digits after +44. For most UK numbers it should be 9 or 10 digits. If you see 10 or 11 and the number seems long, you probably left the leading zero in.
Best Times to Fax the UK from the US
The UK observes two time zones during the year:
- GMT (UTC+0): Late October through late March
- BST — British Summer Time (UTC+1): Late March through late October
| US Time Zone | Offset from UK (winter / summer) | UK Office Hours (9 AM–5 PM) = Send During |
|---|---|---|
| Eastern (ET) | UK +5 / +6 hrs | 4 AM–12 PM ET (winter) / 3 AM–11 AM ET (summer) |
| Central (CT) | UK +6 / +7 hrs | 3 AM–11 AM CT (winter) / 2 AM–10 AM CT (summer) |
| Mountain (MT) | UK +7 / +8 hrs | 2 AM–10 AM MT (winter) / 1 AM–9 AM MT (summer) |
| Pacific (PT) | UK +8 / +9 hrs | 1 AM–9 AM PT (winter) / 12 AM–8 AM PT (summer) |
Most US senders can't send during UK business hours in real time — the windows overlap with the early morning. The practical solution is to use an online fax service that lets you schedule your fax to go out overnight and arrive when UK offices open.
mFax.to supports scheduled sending, so you can queue your document in the evening and have it waiting in the recipient's fax inbox when they arrive at work.
Asynchronous faxing works in your favor
Unlike a phone call, a fax doesn't require both parties to be present at the same time. The receiving fax machine captures the document whenever it arrives. Faxing overnight from the US is normal and widely expected by UK recipients.
Cost of Faxing to the UK
International fax rates vary by service. Online fax services are significantly cheaper than routing an international call through a traditional fax machine and landline.
| Method | Typical Cost | Notes |
|---|---|---|
| Online fax service (per-fax plan) | $2–$5 per fax | Best for occasional faxing |
| Online fax service (subscription) | Included in monthly plan | mFax.to subscription covers many countries |
| Physical fax machine via landline | $0.25–$1.50/min | Expensive for multi-page faxes |
| Traditional phone company | $2–$15 per minute international | Usually the most expensive option |
For detailed country-by-country pricing, see our guide to international fax rates.
A4 vs. US Letter: Does Paper Size Matter?
The UK uses A4 paper (210×297mm), while the US standard is Letter (216×279mm). A4 is slightly narrower and about 18mm taller.
In practice, this rarely causes problems. Modern fax machines and all major online fax services handle both sizes automatically — the receiving machine scales or crops to fit its paper. If you're sending a critical document with content near the page edges, leave at least 10mm of margin on all sides to ensure nothing gets clipped.
If you're building a form or template specifically for a UK audience, consider setting your document to A4 dimensions before faxing so the layout prints cleanly on their end.
GDPR and Faxing Personal Data to the UK
If your fax contains personal information about individuals — names, addresses, medical details, financial data — UK data protection law applies on the receiving end. The UK GDPR (retained after Brexit) and the Data Protection Act 2018 require that personal data be handled with appropriate security measures.
For personal or sensitive faxes, use an online fax service rather than a physical machine. Digital fax services provide:
- Timestamped delivery receipts — evidence the document arrived
- Audit logs — searchable records of what was sent and when
- Secure digital storage — documents aren't sitting in a fax tray where anyone can read them
mFax Business includes delivery tracking and an audit trail — a practical step toward demonstrating appropriate security for cross-border faxes.
Sending Your First Fax to the UK
Whether you're sending a contract to a London solicitor, a healthcare record to an NHS trust, or a purchase order to a UK supplier, the process is the same:
- Get the UK fax number (domestic or +44 format)
- Remove the leading zero from the area code
- Dial 011-44 (fax machine) or enter +44 (online service)
- Send and confirm delivery
The simplest way to send from the US is with mFax.to — open the app or website, enter the +44 number, upload your document, and send. You'll get a delivery confirmation and can schedule the fax to land during UK business hours.
No fax machine. No international calling plan. No per-minute charges.
For a broader look at faxing across borders, including formats for 50+ countries, see our complete guide to international faxing.