ZIP+4 Code™ Lookup | Last 4 Digits of ZIP Codes (2024)

ZIP+4 Codes are 4-digit codes added to 5-digit ZIP Codes that help the USPS to quickly route mail. The last 4 digits of ZIP Code numbers identify segments of USPS delivery routes. Each ZIP+4 Code usually consists of 6-20 delivery points on a street, in a building, or floor in a high-rise.

ZIP plus 4 Codes help to prevent misdelivered, lost, delayed, and returned mail. Including those last 4 digit of the ZIP Code can reduce delivery time by as much as 2 days.

Full 9-Digit ZIP Code Lookup

USPS ZIP+4 Code lookups are a cinch with the right tools, and Smarty provides easy-to-use options for single ZIP+4 Code lookups, looking up ZIP+4 Codes in bulk (up to millions at a time), and ZIP+4 Code lookup via API.

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In this article; we'll cover:

  • Video: Find My ZIP+4 Code or Any ZIP+4
  • What Are ZIP+4 Codes?
  • Full 9 Digit ZIP Code Benefits (ZIP+4)
  • How ZIP Codes Became 9-Digit-ZIP Codes
  • ZIP+4 Code Database
  • What Is My Full ZIP Code?

Video: Find My ZIP+4 Code or Any ZIP+4

Quickly find the last 4 digits of ZIP Code numbers for almost any address in the United States by watching this video.

What Are ZIP+4 Codes?

ZIP+4 Code™ Lookup | Last 4 Digits of ZIP Codes (2)

ZIP+4 Codes are 4-digit codes appended to the original 5-digit USPS ZIP Codes. Using the full ZIP Code with the extra 4 digits when mailing via the USPS ensures the fastest, most accurate mailing possible.

ZIP+4 Codes are also frequently referred to "Plus-Four Codes", "ZIP Code Extensions", "9 digit ZIP Codes", "Full ZIP Codes", or simply "Extended ZIP Codes". No matter what name you use, ZIP plus 4 Codes aid the USPS in sorting and distributing mail effectively.

ZIP plus 4 lookup tools don't just do a full ZIP Code lookup. Before you get the +4 Code, your address is taken through the full address standardization and validation process confirm the address is mailable.

These codes indicate a specific delivery route, meaning the actual path the mail truck would travel in a single drop-off. Usually, this comprises 5 to 20 homes or locations. The USPS also assigns ZIP+4 Codes to PO Boxes. Typically, each PO Box gets its own +4 Code, which often matches the box number.

The extra 4 digits on ZIP Codes identify segments of fluid postal delivery routes. They're not permanent lines, so a 9 digits ZIP Code can change regularly. Five-digit ZIP Codes also change, but they do so infrequently; it's less likely that you will live in a ZIP Code when it changes. Not so for the last 4 digits of Zip Code numbers.

The +4 on a ZIP Code can change as frequently as every 30 days. In fact, 5% of all addresses get their ZIP+4 Code changed each month. Quantity of postal employees, new construction, remapping delivery areas, etc., are just a few things that cause ZIP+4 Code changes.

These are the most up-to-date stats for USPS ZIP+4 Codes, 5-digit ZIP Codes, and USPS delivery points as of this writing in June 2023:

  • 55,916,190 - Total USPS ZIP+4 Codes in the US
  • 19,504,848 - Total USPS ZIP+4 Codes dedicated to PO Boxes (one ZIP+4 Code per PO Box)
  • 36,411,342 - Total USPS ZIP+4 Codes excluding PO Boxes (conventional ZIP+4 Codes)
  • 41,704 - Total USPS 5-Digit ZIP Codes
  • 837 - Average quantity of USPS ZIP+4 Codes per 5-Digit ZIP Code
  • 193,000,000 - Total USPS delivery points in the US
  • 5.3 - Average delivery points per ZIP+4 Code (excluding PO Boxes)

Full 9 Digit ZIP Code Benefits (ZIP+4 Lookup)

ZIP+4 Code™ Lookup | Last 4 Digits of ZIP Codes (3)

Here are a few benefits of looking up ZIP+4 Codes/9-digit ZIP Codes as a part of your address data management or shipping processes.

  • Faster Shipping - Each ZIP+4 Code represents segments of delivery routes that are usually within a single block of the desired delivery point. That simple 9-digit number makes routing more efficient since the USPS knows which mail person will put the letter in the mailbox. Completing ZIP+4s on your mail can speed up processing and delivery, sometimes by as many as two days.
  • Reduce Lost Mail & Misdeliveries - More efficient routing also means fewer opportunities for mistakes along the way.
  • Less Returned Mail - Obtaining ZIP+4 Codes requires validation; that means the address is a valid delivery point. It also means the address information is standardized to the USPS address format. Mail delivery is more reliable with a valid, standardized address with ZIP4 Code since the address data is clearly understood.
  • Save Money with Bulk Mailings - If you send at least 50 packages or more than 200-500 pieces of mail, you may be able to qualify for commercial mailing discounts. By adding ZIP+4 Codes, Delivery Point Barcodes, and sorting/bundling your mail, you can get discounts up to 5% to nearly 60% off the prices you'd pay at the post office.
  • Cleaner Address Data - Addresses must be validated, standardized, and corrected before you get the ZIP+4 Code. So, you get much more than a pretty 9 digit ZIP Code; you get a clean, standard address. Clean, standard addresses are easy to sort and compare. Comparing a table of standardized, verified addresses allows you to identify duplicates, delete redundancies or merge records easily.
  • Enriched Address Data - When you give Smarty an address and ask for the ZIP+4 Code, we give you the ZIP+4 Code along with the validated, standardized address. We also provide up to 45 data points about the address, including county information, lat/long coordinates, time zone, whether the address is residential or commercial, and more data that can be used for business intelligence and to understand your mail recipients better.

That's right. Your mail can show up faster, cheaper, and more reliably if you label things right, plus you get less returned mail. Bet you're ready to do your first full ZIP Code lookup now.

Those benefits are just the beginning. If you're getting the ZIP+4 Code, you're already validating and standardizing the address and address validation improve business results across all types of organizations. Read our ebook to learn how:

How ZIP Codes Became 9-Digit-ZIP Codes

ZIP+4 Code™ Lookup | Last 4 Digits of ZIP Codes (5)

Fully understanding the last four digits of ZIP Codes requires knowing about 5-digit ZIP Codes too.

These are the codes you know. They look like this.

The Zone Improvement Plan (ZIP) was something the USPS came up with to make it easier to ship letters and packages across the country. ZIP helps divide the country into different "zones" according to the distribution of mail, which accelerates sorting and delivery.

On July 1, 1963, the Post Office Department launched the Zone Improvement Plan. At the same time, they introduced the world to Mr. ZIP or "Zippy." Zippy is the official ZIP Code mascot pictured on our ZIP Codes 101 page. They also released the ZIP Code jingle:

As the US population has increased and scattered since 1963, it's been necessary to expand the system to make room for everybody and their dog. That's where the "plus 4" part comes in. We're getting ahead of ourselves, so let's start with the basics.

If you're mailing a letter from Boston to Seattle, the mail carrier in Massachusetts doesn't care what the street address of the destination is. It's what you might call "outside his jurisdiction." He just needs to know which mail carrier to send it to so the appropriate mail carrier can get it to the address.

A postal worker can only cover so much ground on a given day. And since the USPS has a standard of delivering in the rain, sleet, or snow, that rules out the possibility of doing the service of delivery in stages (some today, some tomorrow). That means any given post office only serves what it can reach in a day. ZIP Codes reflect that.

Typically, a ZIP Code ties to a post office; by that, we mean every one of the latter has one of the former. You might think of ZIP Codes as a mailing address for a particular post office. Some handle more than one ZIP Code, but a one-on-one game plan is a standard.

It's essential to note that ZIP Codes aren't "boundaries." They're a collection of delivery routes. They don't follow geographic or administrative boundary lines; they can cross city, county, and statelines. They follow where the delivery trucks go.

Some ZIP Codes are a bit different in function. Among them are "military" ZIP Codes, which include everythingfrom military bases (domestic or otherwise) to battleships at sea. Then there are "unique" ZIP Codes. Businesses and organizations sometimes get a dedicated ZIP Code that they don't have to share with anyone due to the volume of mail they send and receive.

These frequently benefit from bulk mailing discounts since the organization usually has a mail department that (1) presorts mail before giving it to the USPS and (2) distributes mail internally, so the USPS doesn't have to. Like standard ZIP Codes, "military" and "unique" ZIP Codes circumscribe their delivery area. For a more in-depth guide, visit our ZIP Codes page.

ZIP+4 Code Database

For many users, the best way to access the USPS ZIP+4 database is through a CASS Certified USPS address validation vendor. Like Smarty. Since the last four digits of ZIP Codes update frequently, even month-old data isn't reliable. Checking addresses regularly against the database will ensure your data remains clean.

The ZIP+4 Code database can be accessed free directly through the USPS site or the USPS address validation API. In our USPS APIs article, you will find a comprehensive list of uses and limitations of the USPS web-based tool and API. If you need a ZIP+4 Code Database, address validation might scratch your itch better than anything provided by the USPS. You can check out our ebook. It shows how to improve business results in your organization using address validation. Read it here:

What Is My ZIP Code with the Extra 4 Digits?

If you need an answer to, "What is my ZIP Code with the extra 4 digits?" Just click one of the buttons at the top of the page, enter your address, and get your +4 Code instantly. Just remember, it's called a ZIP+4 Code, or simply a ZIP+4.

The quiz will include three things:

  1. ZIP+4 Codes indicate delivery routes.
  2. Using ZIP+4 Codes gets your mail there faster and more accurately.
  3. We at Smarty can get you those codes.

If you want to try it on a single address, you can now use our SingleAddress Verification Tool. Our blindingly fast US AddressVerification API provides the appropriate ZIP+4 Code for every address we process.

Or you could call us instead if you'd rather talk to an actual person. (We'd offer a fakeperson, but we don't have one of those on staff.) Either way, we can help you ZIP your address and ZIPit well.

ZIP+4 Code™ Lookup | Last 4 Digits of ZIP Codes (2024)


What is the 4-digit code with ZIP code? ›

What Are ZIP+4 Codes? ZIP+4 Codes are 4-digit codes appended to the original 5-digit USPS ZIP Codes. Using the full ZIP Code with the extra 4 digits when mailing via the USPS ensures the fastest, most accurate mailing possible.

How many 4-digit ZIP Codes are possible? ›

How many zip codes are possible if there are no restrictions on the digits used? Hence, there are 10,000 possible 4-digit zip codes if there are no restrictions on the digits used.

Are the last 4 digits of a ZIP code necessary? ›

Yes, when using a ZIP+4 ZIP Code, the number must consist of five digits, a hyphen (or dash), and four digits. Improperly labeled mailpieces may progress slower through the mail system and may be returned to sender if the United States Postal Service® is unable to deliver the item.

How do you read a ZIP 4 code? ›

ZIP+4 Codes - The Next Generation

As a rule, each Post Office Box has its own ZIP+4 Code. The +4 on the ZIP Code is often the last four digits of the box number, zero plus the last three digits of the box number, or, if the box number is less than 4 digits, zeros followed by the box number.

Is 11111 a valid ZIP Code? ›

11111 is not a valid five digit ZIP Code. If you check the official USPS website, it will display the message "You did not enter a valid ZIP Code™.". 11111 is the postal code of Vinius, Lithuania.

What do the digits mean in ZIP Code? ›

ZIP Codes are numbered with the first digit representing a certain group of U.S. states, the second and third digits together representing a region in that group (or perhaps a large city) and the fourth and fifth digits representing a group of delivery addresses within that region.

How many zip plus 4 codes are there in the US? ›

There are 41,704 ZIP Codes in the country. ZIP Codes range from 00501, belonging to the Internal Revenue Service in Holtsville, NY, to 99950 in Ketchikan, AK.

What is the difference between ZIP Code and zip 4? ›

The function of the ZIP + 4® is to indicate a more specific area within a ZIP Code™, including the side of the street on which the building is located. The ZIP + 4® enables mail to arrive faster, as it reduces the need for human interaction in a mail center.

What is the maximum digits of ZIP Codes? ›

The most complete ZIP Code is a nine-digit number consisting of five digits, a hyphen, and four digits, which the USPS describes by its trademark ZIP+4. The correct format for a numeric ZIP+4 code is five digits, a hyphen, and four digits.

What if last 4 digits of ZIP code are wrong? ›

As long as the 5 digit zip is correct the letter or package will go to the designated post office via processing plant. When the seller goes to pay for postage, the computer will correct the wrong zip code.

Does wrong ZIP code matter? ›

Will the package still get delivered to the correct address? Writing the wrong ZIP Code with the right address usually causes the letter to be delivered about a day later than if the ZIPCode were correct. As long as the mailing address is correct, the letter will be delivered.

How many digits is a ZIP? ›

A 5-digit number that identifies a particular postal delivery area in the United States.

What are the last 4 digits after my ZIP code? ›

So what do the extra numbers mean? These last 4 digits represent specific delivery routes within delivery areas. This extra detail means an even more precise matching to a more granular level. It could represent a handful of houses on one side of a street, or even a single building that receives a high volume of mail.

What is a valid US ZIP code? ›

A United States postal code, for example, might be either five digits or five digits followed a hyphen (dash) and another four digits (12345-1234). If you are validating US postal codes, allow for both conditions. The following rule validates a field that can be five digits, five digits + dash + 4 digits, or blank.

What happens if you forgot to put the ZIP code on a letter? ›

A letter without a ZIP code may not reach its intended destination. That is because of the way addresses are read by automated postal systems. Rules that are taken for granted when people send mail are actually unusually strict to increase post office efficiency. Processing machines read addresses from the bottom up.

What zip code is 22222 in the US? ›

22222, Arlington, VA Zip Code Map - MapQuest.

Is 12345 a real zip code? ›

The address is technically deliverable with nothing more than a ZIP Code. The ZIP Code 12345 is kind of in Schenectady, NY and it belongs to the General Electric Co.

What city is ZIP code 77777? ›

66 Acres is in Bedias, TX and in ZIP code 77777.

Is a US ZIP code 5 or 9 digits? ›

United States ZIP codes are five numerical digits long. ZIP+4 codes, also known as add-on or plus-four codes, include four additional digits that identify a geographic segment within a ZIP code delivery area.

What is the first zip code in the US? ›

This first-ever ZIP Code was 00601, designating a decent chunk of Puerto Rico as the first Zone Improvement Plan (ZIP) in the United States.

What does 00000 zip code mean? ›

Assuming we are talking about the US, the 00000 zip code does not exist. So why enter it in the database. Just send that postcard to "One Microsoft Way, Redmond, WA" without a zip code and it will get there just fine.

What is the newest zip code? ›

New 85288 Zip Code | City of Tempe, AZ.

How do I verify my address with USPS? ›

Go to the USPS Zip Code Lookup tool at Enter the street address, city, and state in the appropriate fields. Note: The more complete and accurate the address information, the more likely the USPS will be able to validate it. Click “Find.”

Do ZIP Codes repeat in the US? ›

There are no duplicate ZIP Codes. There are some ZIP Codes that are multi-part polygons, but those polygons are usually adjacent.

What is the ZIP 4 and ZIP 5 code? ›

A 5-Digit ZIP code represents a USPS delivery area.

A 9-Digit ZIP code, also known as a ZIP+4 code or an extended ZIP code, includes the same information as the 5-Digit ZIP code, plus additional information about a specific delivery route within the delivery area.

How are ZIP Codes determined? ›

“the five-digit ZIP number is a structured code in which the first digit identifies one of ten large areas of the Nation, and the second digit indicates a State, a geographic portion of a heavily populated State, or two or more less populated States.

How often do ZIP Codes change? ›

Frequency of ZIP Code Changes

It is typical for 10-20 new ZIP codes to be created each year - many of which are for military uses.

What is the longest zip code in the US? ›

Fun Geography Facts About ZIP Codes

The highest ZIP Code number is 99950 in Ketchikan in Alaska.

What is the largest zip code in the United States? ›

The largest ZIP Code in the contiguous U.S. is 89049, Tonopah, NV, at 10,821 square miles. Twenty-four of the top 25 largest ZIP Codes in the country are located in Alaska – ranging from the largest, 99734, at more than 30,000 square miles to 99741 at 7,600 square miles.

What's the longest zip code in the world? ›

The highest ZIP Code number is 99950 in Ketchikan, AK.

Are there any invalid ZIP Codes? ›

11111 is not a valid 5 digit ZIP Code, but there are valid ZIP Codes that start with 111: 11101, 11102, etc. Once position 28 was changed to Y, then MSP considered 11111 as an Invalid zip, because it looked at all 5 digits.

What makes a zip code invalid? ›

Invalid zip code error is displayed when attempting to process a payment from your customer with a billing address outside the U.S. They may have a ZIP code (or Province code) that includes characters that do not meet the U.S. 5 digit standard.

Why does my zip code not match my billing address? ›

The most common cause of this problem is an old zip code assigned to the card itself. Even though you have updated your address with the bank, they may not sync your new address to the credit/debit card. Try the old/outdated postal code(s) on the payment, and it will likely go through.

What happens if you put the right address but wrong postcode? ›

An incorrect address on a parcel can lead to delivery delays and items not getting delivered or lost. Making sure that the postcode on goods sent is correct is critical in ensuring delivery problems do not happen.

Will credit card go through with wrong ZIP code? ›

If the ZIP code does not match with the ZIP code the card-issuing bank has on file in the processing system, the merchant can choose to decline the transaction and take appropriate steps to ensure the card is not being used fraudulently.

Can a ZIP Code be less than 5 digits? ›

Zip codes were originally five digits, which uniquely identify a post office. (Some might have more than one zip code.) Then Zip+4, the nine-digit form was created, where the extra digits identify one side of the street in a block for single family housing, and some number of units in a larger building.

What is bigger than a ZIP Code? ›

More specific geographic values -- There are approximately 50% more census tracts than ZIP Codes. More accurate geographic match -- census tracts are one of the specific geographic units by which census counts are presented; ZIP Code Tabulation Areas are used to approximate the geographic boundaries of ZIP Codes.

What is the last 4 digits of SSN? ›

The SSN Numbering Scheme
  • The first set of three digits is called the Area Number.
  • The second set of two digits is called the Group Number.
  • The final set of four digits is the Serial Number.

Is A ZIP Code the same as a postcode? ›

Zip code refers to a type of postal code and is used primarily in the United States and the Philippines. The postal code, however, is typically utilized by the rest of the countries scattered throughout the world.

What is a ZIP Code on a card? ›

What is a credit card ZIP code or postal code? A credit card ZIP code is the 5-digit zip code from your U.S. billing address. When you make a purchase, the ZIP code you enter must match the ZIP code associated with your official cardholder address.

What is the smallest ZIP code? ›

The lowest ZIP Code number is 00501, unique for the Internal Revenue Service in Holtsville, NY.

What city has the ZIP code 00001? ›

ZIP area 00001 is located in the Dillingham Census Area, state of Alaska.

How do I find my ZIP code location? ›

Find Zip Codes at

If you have an address or partial address, you can find the zip code through USPS Zip Code Lookup, a tool on the U.S. postal service's website. You can also search by city or state, or find all cities that are part of a particular zip code.

Are there 4 digit ZIP Codes? ›

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.

What happens to dead letter mail? ›

Failing that, the items are to be returned to sender. Failing that, they remain in the postal system. Since the 1990s, such items become the responsibility of Mail Recovery Centers. Prior to the 1990s, such lost pieces were forwarded to the Dead Letter Office.

What to do with mail that isn't yours? ›

If you accidentally opened mail that isn't addressed to you, place the contents of the mail back into the envelope, and write “RETURN TO SENDER.” Place it in the local post box or if you are unsure, take it to your local police station.

What is ZIP Code vs PIN code? ›

PIN code stands for Postal Index Number code. Also known as Zip code or area postal code, Pin code is the post office numbering code system used by the postal service of India, India Post. The PIN was first introduced in India on August 15, 1972.

What is a US ZIP Code example? ›

A United States postal code, for example, might be either five digits or five digits followed a hyphen (dash) and another four digits (12345-1234).

What is code or ZIP Code? ›

Zip Code refers to a postal code, used in a few countries with a postal address to specify the location at which mail is sent. On the other hand, postal code indicates the code used in the postal address, which assists in the sorting the mails for the purpose of delivering them at their exact destination.

What are the last 4 digits after my ZIP Code? ›

So what do the extra numbers mean? These last 4 digits represent specific delivery routes within delivery areas. This extra detail means an even more precise matching to a more granular level. It could represent a handful of houses on one side of a street, or even a single building that receives a high volume of mail.

What is the difference between zip5 and zip4? ›

The Zip Plus 4 (9 Digit Zip Code)

Sometimes the extra four digits represent a apartment complex or a city within a zip code. While we usually write only a 5-digit zip code on mail, or when looking up a city, the USPS still uses the zip plus 4 code in order to deliver mail.

What does the first digit of a zip code mean? ›

The first digit in a ZIP code represents a defined group of U.S. states. The second and third digits represent a region in that group, such as a large city. To send mail, only the first five digits of the ZIP code are required.

What are the first 2 digits of your zip code? ›

What each number means. The first digit designates a broad area, which ranges from zero for the Northeast to nine for the far West. The two following digits are the code of a central post office facility in that region. The last two digits designate small post offices or postal zones.

What is an alphanumeric zip code? ›

Alphanumeric postal codes use both letters and digits, and normally encode many more locations than numeric postcodes. This happens because such zip codes are assigned to smaller and more specific locations, such as blocks, for instance.

What is the richest zip code in America? ›

1: Atherton, Calif. (94027)

Where is US zip code 00001? ›

The current postal codes in the United States range from 00001 – 99950. The lowest and highest of these postal codes are both specific to areas in Alaska; The 00001 code is for the N Dillingham area, and the postal code 99950 is for Ketchikan, AK.

What is an example of a zip 4? ›

The segment can be a city block, a group of apartments or other mail receiving units that could benefit from the use of an additional identifier. An example of a ZIP+4 ZIP code is 99577-0727.

Is zipcode always a number? ›

Most of the postal code systems are numeric; only a few are alphanumeric (i.e., use both letters and digits). Alphanumeric systems can, given the same number of characters, encode many more locations.

What is a zip code on a card? ›

What is a credit card ZIP code or postal code? A credit card ZIP code is the 5-digit zip code from your U.S. billing address. When you make a purchase, the ZIP code you enter must match the ZIP code associated with your official cardholder address.


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