What Is A BIN Number & How Does It Work?

As a small business owner, there’s a good chance you handle credit card payments regularly. You may already be familiar with things like CVV codes, card networks, and payment security, but you might not know what a Bank Identification Number (BIN) is or how it works.

This guide breaks it down for you.

What Are Bank Identification Numbers?

Bank Identification Numbers (BINs), also called Issuer Identification Numbers (IINs), are the first several digits on a payment card.

BINs are used to identify the institution that issued a credit card, debit card, prepaid card, or other payment card.

The BIN system is standardized internationally and helps payment processors determine details about a card during a transaction, including the card issuer and card network.

The first digit identifies the card industry or network, while the remaining BIN digits identify the issuing financial institution.

What Are Bank Identification Numbers Used For?

BINs help payment processors and financial institutions identify payment cards and route transactions correctly.

How To Find Your Bank Identification Number

You can find a card’s BIN by looking at the payment card number printed on the front or back of the card.

The BIN is the first several digits of the card number. Traditionally, BINs were the first six digits, though the industry is increasingly moving toward eight-digit BINs.

The first digit identifies the major card industry or network category, while the remaining BIN digits identify the issuing institution.

Common card network prefixes include:

• Visa cards typically begin with 4
• American Express cards typically begin with 34 or 37
• Mastercard cards typically begin with 51–55 or 2221–2720
• Discover cards typically begin with 6011, 65, or certain 64 and 622 ranges

As payment networks expand, eight-digit BINs are becoming more common to increase the number of available issuer combinations without changing the overall card number length.

How Businesses Can Prevent BIN Fraud

Fraudsters can use known BIN ranges to generate and test stolen or fake card numbers online, especially on eCommerce sites with weak fraud controls.

Businesses should monitor transaction activity for signs of card testing fraud, including:

• Large numbers of small transactions
• Repeated declined transactions
• Sudden spikes in transaction volume without a clear business reason

These patterns can indicate that fraudsters are testing card numbers to identify valid accounts.

Regular transaction monitoring, fraud detection tools, AVS checks, CVV verification, velocity limits, and payment processor fraud filters can all help reduce the risk of BIN-related fraud.

The Bottom Line On Bank Identification Numbers

Bank Identification Numbers help payment systems identify card issuers, process transactions, and detect potential fraud.

Understanding how BINs work can help businesses better recognize suspicious transaction activity and understand how card payments are routed and authorized.

Want to know more about business banking? Start with learning why you need a business bank account. Then, we make it easy to help you choose the best bank for your business and open a business bank account.