ZIP+4 Code™ Lookup Tool & Extra 4 Digits of ZIP Codes Explained

4 minute read

ZIP+4 Codes are an extension of the traditional 5-digit ZIP codes used by the USPS, providing a more precise way to identify specific groups of delivery points within a given ZIP code. Each ZIP+4 code can represent a range of delivery points, such as a block of apartments or a group of businesses, as well as individual delivery points.

Looking up ZIP+4 codes can be easy with the right tools. The USPS provides a free ZIP Code lookup service on their website that allows users to find ZIP+4 codes for specific addresses or ranges of addresses. If you find the USPS ZIP Code lookup service doesn’t meet your needs, Firstlogic offers an easy-to-use lookup tool below that provides accurate and up-to-date information. With the Firstlogic tool, you can quickly search for ZIP+4 codes by entering an address or partial address.

ZIP+4 Code Lookup

Lookup the full ZIP+4 code for an address using our free tool

If using the USPS tool is more your speed, read on for a step-by-step guide.

Looking up a ZIP+4 with the USPS ZIP Code™ Lookup Tool

The USPS ZIP Code™ Lookup Tool is a free web-based tool that allows users to find ZIP+4 codes for specific addresses or address ranges. Here’s how to use the tool:

  1. Go to the USPS website and navigate to the ZIP Code™ Lookup Tool page:
  2. Enter the address you want to look up in the “Street Address” field. You can also enter a city and state or a ZIP code to narrow down your search.
  3. Click the “Find” button to search for the ZIP+4 code associated with the address.
  4. The tool will display the ZIP+4 code for the address, as well as additional information such as the 5-digit ZIP code, the delivery point code, and the carrier route code.
  5. If you need to look up multiple addresses or perform batch processing, you can download the USPS ZIP+4 Code file, which contains the full list of ZIP+4 codes for all valid delivery addresses in the United States.

By using the USPS ZIP Code™ Lookup Tool, you can easily and quickly find accurate and up-to-date ZIP+4 codes for your mailing needs. However, it’s important to note that the usage of this tool is subject to terms of service and usage limits that may not be sufficient for all needs. In such cases, third-party providers like Firstlogic may provide a more robust and customizable solution for ZIP+4 code lookup needs.

What are ZIP+4 Codes?

Zipcode ZIP+4 meaning and digit reference
An example of the data represented by each digit of a ZIP+4 code.

ZIP+4 codes, also known as Plus-Four codes, ZIP code extensions, 9 digit ZIP codes, extended ZIP codes, or full ZIP codes, are four-digit codes that are appended to the traditional five-digit USPS ZIP codes. When used in conjunction with the full ZIP code, the additional four digits allow for more accurate and efficient mail delivery.

Each ZIP+4 code represents a specific delivery route, which typically includes 10 to 20 homes or locations. These routes are not permanent and can change regularly, making the last four digits of ZIP codes more volatile than the first five digits. Factors such as the quantity of postal employees, new construction, and remapping of delivery areas can all contribute to changes in ZIP+4 codes.

Due to the dynamic nature of ZIP+4 codes, it’s important to keep address lists and mailing labels up to date with the most current ZIP+4 codes available. Using an accurate and up-to-date ZIP+4 code lookup tool, such as the ones mentioned earlier in this article, can help ensure that your mail is delivered to the correct location in a timely and efficient manner.

What Is My ZIP Code with the Extra Four Digits?

If you need the answer to: “What is my ZIP Code with the extra 4 digits?”, we suggest you find the “Use Now” button at the top of the page, enter your address, and get your ZIP+4 Code instantly. Remember, your ZIP code “with the extra 4 digits” is also better known as a ZIP+4 Code.


The USPS provides a free ZIP+4 code lookup tool on their website that can be used to find accurate and up-to-date ZIP+4 codes for specific addresses. By using this tool, individuals and businesses can ensure that their mail is delivered to the correct location in a timely and efficient manner.

Using a reliable and accurate ZIP+4 code lookup tool, whether from the USPS or a third-party provider like Firstlogic, can help ensure that your mail is delivered accurately and on time. By reducing the chances of misdeliveries or returned mail, businesses can improve customer satisfaction and reduce costs associated with undeliverable mail.