People look for the sort code on a card because that is where it used to be, printed in small digits under the name. On a lot of current UK cards it is no longer there at all, and on some it never was. That is a deliberate change rather than an oversight, and once you know why, finding the number somewhere else takes a few seconds.
Where it appears when it does appear
On an older UK debit card the sort code and account number are printed together on the front, usually beneath the cardholder name, with the sort code shown as three pairs of digits and the account number as eight digits beside it. Some banks moved the pair to the reverse of the card. Neither location has anything to do with the long card number across the middle, which is a card number and not an account number, and which will not work as a payment destination.
Why newer cards are blank
Several UK banks now issue cards with no printed account details, and some issue cards with nothing printed on the front at all. The reasoning is straightforward: a card that carries your sort code, account number and name is a complete payment instruction if it is lost or photographed, and a card that carries none of them is not. Card details and account details are now deliberately separated, which is why the app has become the place to read the account details rather than the plastic.
Where to read it instead
Open your banking app and look for the account details or share details screen, which exists precisely so you can pass the sort code and account number to a payer. A statement header carries the same pair. So does a paying in book if you still have one. If you are on the telephone to the bank they will confirm it after identifying you. All four of those are sources you control, which matters more than convenience when the number is going to be used to move money.
The number on the card that is not a sort code
The long number on the front of a card is the card number, and the six digits at its start identify the issuer scheme rather than a UK clearing point. It is easy to mistake for an account identifier because it is long and it is printed on a bank product, but no UK bank transfer will accept it. If a payment form asks for a sort code and account number, the card number is never the answer, and a request to pay a card number for a bank transfer is a common shape of scam.
Questions people ask about what is the sort code on a card
Is the sort code the first six digits of my card number?
No. The long card number is a card scheme number. The sort code is a separate six digit code, and the two are unrelated.
My card has nothing printed on it. Is that normal?
Yes. Several UK banks now issue cards with no printed details as a fraud measure, and the account details live in the app instead.
Can I use the sort code from an old card?
Only if the account is the same one. A replacement account, a switched account or a moved product can carry different details, so read the current pair from the app or a recent statement.
Where is the account number on the card?
Where a card prints details at all, the eight digit account number sits beside the six digit sort code, normally under the cardholder name.