This free UK phone number checker shows whether a number is valid.
A UK phone number checker tells you whether a number is real, which means it follows the UK's numbering rules and is assigned. Enter a +44 number above and 1Lookup's free checker returns valid or invalid in seconds, with the line type and country, checked against the UK's numbering plan.
Pick the country, then enter the number without the country code.
Free & rate-limited. No signup required to try.
- Country code
- +44
- Mobile numbers
- 10 digits after +44, or 11 written at home, starting 07
- Landlines
- 10 digits after +44, starting 01 or 02, such as +44Â 20Â XXXXÂ XXXX
- Written at home
- 07400 123456
- Written for apps and SMS
- +447400123456
- Dialed from the US
- 011 44 7400 123456
A UK mobile number is +44 followed by 10 digits, and the first one is 7.
Written with the country code
- +44Country code
- 7Mobile start
- 400 1234569 more digits
Written at home
- 0Replaces +44
- 7Mobile start
- 400 1234569 more digits
The +44 and the 0 do the same job, so a number is never written with both.
A UK phone number checker reads a number's format first and then checks it against the UK's numbering plan.
This is the path one check takes. A number can be written correctly and still not be assigned to anyone, so the format check alone is not the answer.
- You enter the numberType it the way it is written at home, such as 07400 123456, or paste it with +44.
- Its format is checkedEach type of number has its own rules. A mobile needs 10 digits after +44 and starts with 07 at home.
- It is checked against the numbering planNumbers outside the US and Canada are checked against the numbering plan of their country, which for this page is the UK's.Nothing is sent to the number, so it never rings and its owner is never told.
- You see valid or invalidWith the line type and country in a few seconds, and the carrier or network where one is listed.
A UK mobile number has 10 digits after +44 and starts with 07, so any other length is not a valid mobile.
These lengths come from the numbering data for the UK. A mobile number has 11 digits when it is written at home with its 0.
| Number type | Starts with at home | Digits after +44 | Written at home |
|---|---|---|---|
| Mobile | 07 | 10 | 07400 123456 |
| Landline | 01 or 02 | 10 | 020 XXXX XXXX |
Three common mistakes make a UK number fail the check, and each one is quick to fix.
Keeping the 0 after +44 adds a digit.
The 0 is only for dialing inside the UK, so +44 07400 123456 is wrong. Drop the 0 and write +44 7400 123456.
Typing too few or too many digits makes a number invalid.
A mobile number has 10 digits after +44. With 9 or 11 it cannot be a valid mobile, so look for a missing or doubled digit.
Leaving the wrong country selected changes how the number is read.
The checker reads a number by the rules of the country selected above, so keep the UK selected for a +44 number. Paste a number with its + and country code and the country is read from the number itself.
These are the questions people ask most about checking UK phone numbers.
How do I check if a UK phone number is valid?
Enter the number in the box above with the UK selected. The free checker returns valid or invalid in seconds, with the line type and country. Type it the way it is written at home, such as 07400 123456, or in full as +44 7400 123456.
How many digits is a UK phone number?
A mobile number has 10 digits after +44, or 11 written at home. A landline has 10 digits after +44, such as +44 20 XXXX XXXX.
What does a UK mobile number start with?
Mobile numbers start with 07 at home, which is 7 after +44. The next digit is 1, 2, 3, 4, 5, 7, 8 or 9.
How do I write a UK number for an app or an SMS tool?
Use the E.164 form: a plus sign, 44, then the number without its leading 0 and no spaces, such as +447400123456.
Does the UK phone number checker show the carrier?
It shows the carrier or network where one is listed. Numbers outside the US and Canada are checked against the numbering plan of their country rather than live carrier data, so some come back with no carrier name.
Does valid mean the UK number is active?
No. Valid means the number is real, correctly written for the UK and assigned. Whether a line is switched on and reachable right now is a different question, and the free HLR lookup answers it.
Can I check a whole list of UK phone numbers?
Yes. This free tool checks one number at a time. A 7-day free trial opens CSV upload and the API, at 1 credit a number.
Does the person know I checked their number?
No. The check reads records only. No call or text goes to the number, so its owner is never told.
You can check numbers from other countries on their own pages.
These free tools answer the next question about a number.
- The +44 country code pageHow to dial the UK, the time there now and the landline places.
- HLR lookupCheck whether a mobile number is switched on and reachable right now.
- Line type lookupSee whether a number is a mobile, a landline or VoIP.
- Carrier lookupFind the carrier or network behind a number.
- Phone validator for any countryThe same check with the country picker open to every country.
- Phone validation APIRun the same check from your own software, one request per number.
Sources: Google's libphonenumber numbering data for lengths, mobile starts and landline starts, as of September 24, 2026; the ITU list of country codes.