The global cross-border payment market was valued at $212.55 billion in 2024 and that value is expected to increase steadily over the next few years. If you handle cross-border payments, open international bank accounts, or build products that move money between the UK and the US, you might have wondered what the difference is between a sort code and a routing number. These aren’t interchangeable, and the distinction is important for companies that do business in these countries.

Below, we’ll explain what a sort code is, what a routing number is, and how a sort code vs. routing number works.

What’s in this article?

• What is a sort code?
  
• What is a routing number?
  
• What is the difference between a sort code and a routing number?
  
• How does a sort code work in UK banking?
  
• How does a routing number work in the US banking system?
  
• How do you find your sort code or routing number?
  
• How Stripe Payments can help
  

What is a sort code?

A sort code is a six-digit number used in the UK (and Ireland) to identify a bank and the specific branch where an account is held. It tells the payment networks which bank should receive the funds before the account number directs the money to the right customer.

What is a routing number?

A routing number is a nine-digit code used in the US to identify a bank or credit union in domestic payments. Also known as an American Bankers Association (ABA) routing number, it directs transfers through the Federal Reserve system so money reaches the correct financial institution.

What is the difference between a sort code and a routing number?

A sort code is six digits, usually written in three pairs (e.g., 12-34-56). A routing number is nine digits with no formatting breaks. While a sort code traditionally identifies a specific bank branch, a routing number identifies the bank as an institution within the US Federal Reserve system and might vary by state or payment type. Cross-border payments that originate in the UK embed the sort code in the International Bank Account Number (IBAN). US routing numbers aren’t incorporated into IBANs in the same way.

How does a sort code work in UK banking?

When you send money via Clearing House Automated Payment System (CHAPS), Bacs, or Faster Payments, the sort code is the first filter the system reads. It determines which bank the payment instruction is sent to. This allows the network to route it correctly before it credits the individual account, which is identified next by using the eight-digit account number.

With Faster Payments, the sort code is checked almost instantly to validate the destination bank. In Bacs, it’s used in batch processing to group and route large transaction volumes efficiently. CHAPS uses it to ensure high-value, same-day transfers reach the correct institution without manual intervention.

While sort codes were originally tied to specific high street branches, modern banks often centralize operations. Many digital banks use a single sort code for all customers. The combination of sort code and account number still uniquely identifies the account, and UK banks use name check systems such as Confirmation of Payee, which cross-reference the account name with the sort code and account number. This adds a layer of protection against misdirected payments and authorized push payment fraud.

Sort codes must be entered correctly in order for the transaction to proceed as intended. A single incorrect digit in a sort code can cause a payment to fail or, in less common cases, be routed to the wrong institution. Because funds are often processed quickly, it can be difficult to correct errors after the fact.

How does a routing number work in the US banking system?

The routing number tells the Federal Reserve system which financial institution should receive the funds. The first four digits correspond to the Federal Reserve district and processing center, the next four identify the specific bank, and the final digit is a checksum used to detect entry errors. Large US banks often operate under several routing numbers depending on state, region, or payment type. Using the wrong routing number can lead to rejected or delayed transfers.

ACH transfers

Payments that run through the Automated Clearing House (ACH) network use the routing number to reach the appropriate bank. These payments are often used for payroll, recurring debits, vendor payments, and other electronic bank transfers, and they’re processed in batches.

Wire transfers

High-value or time-sensitive wire transfers include the routing number in the instructions to direct the funds correctly. Some banks use separate routing numbers for wire transfers vs. ACH payments. Use the correct one.

How do you find your sort code or routing number?

The fastest option is usually your digital banking portal. The account details section clearly lists your sort code or routing number alongside your account number. Paper or PDF bank statements typically show the sort code and account number near the top for UK accounts. US statements also often include the routing number, although presentation varies by bank.

UK checks display the sort code in the string of numbers printed along the bottom, while US checks include the routing number on the bottom left as the first nine-digit sequence. Account-opening documents, confirmation letters, and downloadable account details typically include the relevant code as well.

If there’s any uncertainty, particularly in the US where banks might use different routing numbers for ACH and wire transfers, it’s worth confirming with your bank to avoid rejected or delayed payments.

How Stripe Payments can help

Stripe Payments provides a unified, global payment solution that helps any business—from scaling startups to global enterprises—accept payments online, in person, and around the world.

Stripe Payments can help you:

• Optimize your checkout experience: Create a frictionless customer experience and save thousands of engineering hours with prebuilt payment UIs, access to 125+ payment methods, and Link, a wallet built by Stripe.

• Expand to new markets faster: Reach customers worldwide and reduce the complexity and cost of multicurrency management with cross-border payment options, available in 195 countries across 135+ currencies.

• Unify payments in person and online: Build a unified commerce experience across online and in-person channels to personalize interactions, reward loyalty, and grow revenue.

• Improve payment performance: Increase revenue with a range of customizable, easy-to-configure payment tools, including no-code fraud protection and advanced capabilities to improve authorization rates.

• Move faster with a flexible, reliable platform for growth: Build on a platform designed to scale with you, with 99.999% historical uptime and industry-leading reliability.

Learn more about how Stripe Payments can power your online and in-person payments, or get started today.