Understanding Credit Card Prefixes: 4400, 5466 and 6011


Abhinil Kumar


May 11, 2024

AI powered financial assistants

A credit card is a financial tool that allows individuals to make purchases on borrowed funds. It serves as a convenient alternative to carrying cash and enables consumers to make purchases without immediate payment. The primary purpose of a credit card is to provide individuals with a line of credit that they can use to make purchases and pay back at a later date.

One key feature of credit cards is their worldwide acceptance. Credit cards are accepted at millions of locations globally, making them a convenient payment method for individuals who travel frequently or make international purchases. Cardholders also enjoy zero fraud liability, meaning that they are not held responsible for unauthorized transactions made using their credit card. This provides a sense of security and peace of mind to users.

Moreover, credit card companies typically offer cardmember services 24/7. This means that cardholders have access to customer support around the clock, allowing them to address any issues or concerns they may have regarding their credit card. Additionally, many credit cards come with various benefits such as cashback rewards, travel insurance, and purchase protection, providing cardholders with additional value for their purchases.

This guide explores what the numbers 4400, 5466, and 6011 indicate about a credit card, delving into the type of cards these numbers represent and what potential cardholders can expect from them.

What is a Bank Identification Number (BIN)?

BIN, which stands for Bank Identification Number, or IIN, which stands for Issuer Identification Number, refers to the first six digits of a bank card number or payment card number. These digits play a crucial role in identifying the financial institution that issued the card.

The purpose of BIN or IIN is to provide a standardized way of identifying and categorizing the thousands of cards issued by different banks and financial institutions. Each institution is assigned a unique BIN or IIN, which helps in streamlining processes such as card acceptance, authorization, and fraud detection.

BIN or IIN are particularly relevant in credit cards, debit cards, and other similar cards because they ensure that the cardholders' transactions are accurately and securely processed. These numbers enable merchants, payment processors, and other parties involved in card transactions to quickly determine which bank or institution issued the card, allowing for seamless communication between different entities in the payment ecosystem.

The concept of BIN or IIN is defined by the international standard ISO/IEC 7812, which sets guidelines for the structure and allocation of these identification numbers. This standard ensures compatibility and interoperability across different payment systems and networks worldwide.

Structure of Credit Card Numbers

The structure of credit card numbers is purposefully designed to ensure security and provide essential information about the card. Each credit card number consists of several components that serve different purposes.

First, the credit card number itself reveals the type of card it is. For example, Visa cards start with the number 4, Mastercard cards begin with 5, and American Express cards start with 3. This identification of the card type helps in categorizing and recognizing the card at a glance.

The next part of the credit card number is the issuer identification. This segment identifies the financial institution or bank that issued the card. It is a unique identifier assigned to each card issuer, allowing for easy recognition and organization.

To ensure the validity of credit card numbers, the Luhn Algorithm is employed. This algorithm uses a mathematical formula to verify the accuracy of the card number. By applying specific calculations and cross-checking the results with a check digit, the algorithm determines if the credit card number is valid or not.

Lastly, credit card numbers contain a unique identification aspect called the account identifier. This segment is a unique number assigned to each cardholder and serves as a way of differentiating individual accounts within the same card type and issuer.

Meaning behind the First Four Digits

The first four digits of a credit card number are significant in identifying the card issuer. Each financial institution or card issuer is assigned a unique identification number known as the Bank Identification Number (BIN). The BIN is the first six digits of the credit card number, with the first four digits being particularly crucial in determining the card issuer.

For instance, the most popular card types, such as Visa, MasterCard, and Discover, have specific first digits. Visa cards always start with a 4, while MasterCard cards begin with a 5. Discover cards, on the other hand, usually start with the digits 6011.

American Express, Diner's Club, and Carte Blanche share the first digit, which is always a 3. However, the following digits differ to further differentiate between these card issuers.

Additionally, other card issuers have their own unique first digits. For instance, cards issued by JCB in Japan start with the digit 35. Similarly, cards issued by Dankort, a popular card in Denmark, begin with the digits 5019.

Decoding the Numbers: The Role of BIN/IIN

Credit card numbers are not random. They follow a structured format that complies with the ISO/IEC 7812 numbering standard. The first six digits, known as the BIN or IIN, identify the institution that issued the card to the cardholder. This numbering system helps in streamlining transactions, enhancing security, and facilitating rewards programs tailored to specific consumer needs.

  • 4400 – This prefix is commonly associated with Visa branded debit and credit cards issued by various banks. Cards that start with 4400 are part of Visa’s extensive network and are widely accepted both domestically and internationally.
  • 5466 – Credit cards that begin with 5466 are typically MasterCard products. MasterCard uses this series to categorize a specific portfolio of its offerings, which often includes credit cards tailored for everyday purchases as well as rewards-focused financial products.
  • 6011 – The 6011 prefix is famously linked to Discover cards. This series indicates that the card is part of the Discover network, known for cash back rewards and a user-friendly approach to credit management.

Features and Benefits: What to Expect

Each card issuer provides a unique set of features that cater to various demographics and spending habits. Understanding these can help potential cardholders choose the card that best suits their needs.

Visa Cards (4400)

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Visa cards are renowned for their security and global acceptance. They often come with benefits such as:

  • Fraud protection: Visa offers comprehensive fraud liability protection, ensuring cardholders are not held responsible for unauthorized transactions.
  • Global acceptance: With Visa’s extensive network, cardholders can make purchases almost anywhere around the world.
  • Reward programs: Visa partners with numerous retailers and service providers to offer cash back, points, and other rewards.

MasterCard (5466)

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MasterCard cards are equally popular, offering distinct advantages such as:

  • Price protection: Some MasterCard options come with price protection policies that refund the difference if an item purchased with the card is found cheaper elsewhere within a specific time frame.
  • Exclusive offers: MasterCard often provides access to exclusive deals and experiences, ranging from travel upgrades to dining and entertainment.
  • Enhanced security: Features like MasterCard SecureCode add an extra layer of security during online transactions.

Discover Cards (6011)

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Discover is known for its customer-centric features, including:

  • Cash back rewards: Discover cards are particularly favored for their generous cash back rewards on various categories of purchases.
  • U.S.-based customer service: Discover prides itself on providing top-tier customer service, which is all U.S.-based.
  • No annual fees: Many Discover cards come without any annual fees, reducing the cost of holding the card.

Choosing the Right Card: Considerations

When selecting a credit card, consider factors such as the intended use, benefits, interest rates, and your financial situation. Whether it’s for managing business expenditures, funding personal shopping sprees, or accumulating travel points, the right card can offer more than just credit—it can also bring substantial savings and rewards.

  • Interest Rates and Fees: Always review the APR and associated fees before applying for a credit card.
  • Reward Suitability: Match the card’s reward programs with your spending habits to maximize benefits.
  • Credit Requirements: Some cards require a higher credit score for approval. Ensure you meet these criteria to increase your chances of approval.


The initial numbers on a credit card, known as the Bank Identification Number (BIN) or Issuer Identification Number (IIN), play a critical role in the financial industry. They help identify the issuing institution and card type, facilitating secure and efficient payment processing. Cards starting with 4400, 5466, and 6011 exemplify the variety and specialization in today's credit card offerings, each associated with major networks like Visa, MasterCard, and Discover. These networks provide a range of products designed to meet diverse consumer needs, from basic purchasing power to complex reward structures and security features.


What do the numbers 4400 on a credit card signify?
The numbers 4400 on a credit card indicate that the card is issued under the Visa network. Visa cards with this prefix are known for their widespread acceptance and often come with security features and rewards programs designed to enhance purchasing experiences globally.

Are credit cards that start with 5466 part of the Visa or MasterCard network?
Credit cards starting with 5466 belong to the MasterCard network. MasterCard uses this series for a variety of card types, offering benefits such as global acceptance, enhanced security measures, and access to exclusive deals and promotional offers.

What can I expect from a Discover card that starts with 6011?
Discover cards with the 6011 prefix are known for their cash back rewards and consumer-friendly policies. These cards often feature no annual fees, a U.S.-based customer service team, and generous rewards on everyday purchases.

How do card issuers like Visa and MasterCard ensure the security of transactions?
Visa and MasterCard ensure transaction security through multiple layers of protection, including real-time fraud monitoring, encrypted transactions, and zero liability policies for unauthorized purchases. They also offer secure technologies like EMV chips and contactless payment options to further safeguard consumer data.

Can I use my Discover, Visa, or MasterCard internationally?
Yes, Visa and MasterCard are widely accepted globally, making them excellent choices for international travel and purchases. Discover cards are also accepted in many countries, though their international acceptance is not as extensive as Visa and MasterCard. Always check the specific card’s acceptance before traveling abroad to ensure convenience and security.