To call the UK from the US, dial 011 (the US exit code), then 44 (the UK country code), then the UK number without its leading 0. A London number written 020 7946 0123 becomes 011 44 20 7946 0123. On a cell phone you can press and hold 0 to get a + and dial +44 20 7946 0123 instead.
That one rule, dropping the 0, is where most failed calls to Britain come from. This guide covers it, plus how UK mobile and landline numbers look, which numbers behave differently, the time difference from every US time zone (including the odd weeks when it shifts by an hour), what it costs and how to text.
The short version
| What you dial | For the UK | Notes |
|---|---|---|
| US exit code | 011 | Or + on a cell phone |
| Country code | 44 | Covers England, Scotland, Wales and Northern Ireland |
| Trunk prefix | 0 (drop it) | UK numbers are written with a leading 0 for calls inside the UK |
| Number after the 0 | Usually 10 digits | For example 20 7946 0123 or 7700 900123 |
| Full pattern | 011 44 + number without the 0 | +44 on a cell phone |
Step by step from a US phone
- 1. Write down the full UK number: UK numbers are usually shown as 11 digits starting with 0, such as 020 7946 0123 (London) or 07700 900123 (a mobile).
- 2. Remove the leading 0: The 0 is the UK trunk prefix, used only for calls inside the UK. From abroad it must go. 020 7946 0123 becomes 20 7946 0123.
- 3. Dial 011, then 44: From a US landline or office phone, dial 011 44. From a cell phone, + replaces 011, so dial +44.
- 4. Dial the rest of the number: Spaces don't matter. The full call is 011 44 20 7946 0123, or +44 20 7946 0123 on a cell phone.
- 5. Save contacts with +44: Saving UK contacts as +44 numbers means they work from the US, from the UK when you travel, and in WhatsApp.
UK number formats
Ofcom, the UK regulator, runs the national numbering plan. The first digits after the 0 tell you what kind of number you're calling:
| Starts with (in the UK) | What it is | From the US |
|---|---|---|
| 01 and 02 | Landlines tied to an area, such as 020 (London), 0161 (Manchester) or 0131 (Edinburgh) | 011 44 + area code without the 0 + local number |
| 07 (most of the range) | Mobile phones | 011 44 7… (same rule, drop the 0) |
| 070 | Personal numbers, which redirect calls and are not mobiles even though they look like one | Often charged differently; check before you rely on one |
| 03 | National numbers used by businesses, charities and public bodies, priced like a landline call inside the UK | 011 44 3… |
| 0800 and 0808 | Freephone numbers, free inside the UK | Often not reachable from abroad; ask for a geographic or 03 alternative |
Area codes vary in length (020 for London, 0161 for Manchester, longer codes for small towns), but the total is usually 10 digits after the 0. You don't need to know where the area code ends; just drop the 0 and dial the rest.
Worked example
These examples use numbers Ofcom reserves for TV and radio drama, so they are guaranteed not to belong to anyone: London landlines 020 7946 0000 to 0999, and mobiles 07700 900000 to 900999.
| Written in the UK as | Dial from a US landline | Dial from a US cell phone |
|---|---|---|
| 020 7946 0123 (London landline) | 011 44 20 7946 0123 | +44 20 7946 0123 |
| 07700 900456 (mobile) | 011 44 7700 900456 | +44 7700 900456 |
| +44 (0)20 7946 0123 (common on websites) | 011 44 20 7946 0123 (skip the (0)) | +44 20 7946 0123 |
The +44 (0) style you see on UK websites is a hint: the (0) in brackets is only dialed from inside the UK. From the US, leave it out.
Time difference from the US
The UK runs on Greenwich Mean Time (GMT, UTC+0) in winter and British Summer Time (BST, UTC+1) in summer. For most of the year the gap to the US is the one in this table:
| US time zone | UK is ahead by (most of the year) | 9 a.m. in New York is |
|---|---|---|
| Eastern (New York) | 5 hours | 2 p.m. in London |
| Central (Chicago) | 6 hours | |
| Mountain (Denver) | 7 hours | |
| Pacific (Los Angeles) | 8 hours | |
| Alaska | 9 hours | |
| Hawaii (no daylight time) | 10 hours in UK winter, 11 in UK summer |
The daylight-saving caveat: the US and the UK change clocks on different dates. The US springs forward on the second Sunday in March and falls back on the first Sunday in November. The UK changes on the last Sunday in March and the last Sunday in October. So for two to three weeks in March and about one week around Halloween, the gap shrinks by an hour (New York is 4 hours behind London, not 5). In 2026 the UK fell back on October 25 and the US falls back on November 1. In 2027 the US springs forward on March 14 and the UK on March 28.
A good window for business calls is 9 a.m. to noon Eastern, which is 2 p.m. to 5 p.m. in the UK. From the West Coast, that means calling first thing in the morning.
What it costs
We're not quoting rates here because they change often and depend on your plan. What to check before you call:
- Your cell plan: Many US plans charge per minute for calls to the UK unless you add an international calling feature. Your carrier's international rates page lists the current price for UK landlines and UK mobiles, which are sometimes priced differently.
- Landlines and office phones: Business VoIP and landline plans often include some countries and bill others per minute. Check your provider's rate table for "United Kingdom" and "United Kingdom mobile".
- Calling apps: Internet calling apps (WhatsApp, FaceTime Audio, Skype-style apps) are free app to app over Wi-Fi or data. Calls to a real UK phone number from an app usually cost credit.
- Special numbers: UK freephone (0800, 0808) numbers may not connect from abroad, and premium numbers (09) can be expensive or blocked. Look for an alternative 01, 02 or 03 number on the company's site.
Texting and WhatsApp
Regular texts (SMS) from a US cell phone to a UK mobile use the same +44 format: +44 7700 900456. Whether that costs extra depends on your plan, so check before sending a lot. Texts to UK landlines generally don't work.
WhatsApp is widely used in the UK. To add a UK contact, save the number in your phone with a plus sign, the country code and no leading 0, for example +44 7700 900456. WhatsApp's own help page uses a UK number to show exactly this rule. Once saved, the contact appears in WhatsApp, and calls and messages between apps are free over Wi-Fi or data.
Common mistakes
- Keeping the 0: 011 44 020… will fail. It's 011 44 20….
- Dialing the (0) in +44 (0)20: the bracketed 0 is for callers inside the UK only.
- Dialing 00 instead of 011: 00 is the exit code used in the UK and most of Europe, not in the US.
- Calling at 9 a.m. Pacific and expecting a London office to be open: it's 5 p.m. there.
- Assuming an 070 number is a mobile: it's a personal redirect number and may cost more.
Sources
Country code and dialing prefixes: ITU list of E.164 assigned country codes and ITU dialing procedures (international and national prefixes). UK number ranges: Ofcom, Telecoms numbering and Ofcom, What are 03 numbers?. Fictional numbers: Ofcom, Numbers for drama. Clocks: GOV.UK, When do the clocks change? (last Sunday in March to last Sunday in October; the same dates apply across the EU) and 15 U.S.C. § 260a (US daylight saving time runs from the second Sunday in March to the first Sunday in November). WhatsApp format: WhatsApp Help Center, How to add an international phone number. All checked October 19, 2026.
Where Chargezen fits
To be clear up front: Chargezen isn't an international calling service. It doesn't sell calling plans or numbers in the UK; its numbers are US (+1) numbers only. For calls to the UK, use your carrier, a calling app or WhatsApp as described above.
Where it helps is the other direction, when customers in the UK reach your US business. From a UK phone, customers dial 00 1 and your 10-digit US number (or +1 on a mobile). Because the UK is five hours ahead of the East Coast, their working morning is your middle of the night. Concierge answers calls on your US number day and night, from the business details you give it, so a call that lands at 3 a.m. your time still gets answered. When a caller needs a person, Concierge alerts your team in the Finn app and the browser, and a teammate can join the live call. Calls, texts and notes for each customer stay in one thread in the team inbox.
See the phone channel and the AI receptionist, get a local or toll-free US number, or bring the number you already have. If you sell subscriptions to customers abroad, see international subscriptions.
Related terms: VoIP, toll-free number and number porting. Related guides: how to call Germany from the US, how to call Spain from the US and how to get a business phone number. See also how to call the US from the UK and how to call Ireland from the US.
Frequently asked questions
What is the country code for the UK?
44. From the US, dial 011 44 before the UK number, without its leading 0. On a cell phone, use +44.
Do I dial the 0 when calling a UK mobile from the US?
No. A mobile written 07700 900456 is dialed 011 44 7700 900456 from the US.
How many hours ahead is the UK?
Five hours ahead of US Eastern time and eight ahead of Pacific for most of the year, and one hour less for a few weeks in March and around the end of October, when the two countries' clocks change on different dates.
Can I call a UK 0800 number from the US?
Often not. UK freephone numbers are free from UK phones and may not connect from abroad. Look for a regular 01, 02 or 03 number on the company's website.
Can Chargezen call UK numbers?
Chargezen isn't an international calling service and offers US (+1) numbers only. Use your carrier or a calling app for UK calls. Chargezen answers calls that UK customers make to your US number.
