US ZIP code lookup

What is a US ZIP code?

A ZIP code is the postal code system used by the United States Postal Service (USPS), introduced in 1963. ZIP stands for Zone Improvement Plan — a plan to improve the routing of mail delivery. Each ZIP code represents a group of addresses within the same sorting area, helping mail and parcels route to the right delivery office.

A basic ZIP code has 5 digits (e.g. 90001 for Los Angeles, California). The first digit identifies a broad group of states by region; the next two digits identify a regional sorting center; the last two digits identify a specific delivery office or area. USPS also uses the ZIP+4 format (e.g. 90001-1234) to pin down an exact block of addresses — but for international shipping, the 5-digit code is enough.

A ZIP code is completely different from a state code (two letters, like CA, TX, NY) or an area code. A complete US address always includes all three: city, state code, and ZIP code. If you need help writing a US address correctly, see our guide to shipping to the USA.

Why do you need a ZIP code when shipping to the US?

When shipping from Vietnam to the US, the recipient's ZIP code is required information on the international shipping label. Carrier systems like DHL, FedEx, and UPS use the ZIP code to sort and route parcels from the moment they're received. A missing or incorrect ZIP code can delay a parcel, send it down the wrong route, trigger an address-correction fee, or get it returned to sender.

A ZIP code also directly affects shipping cost and delivery time. Many carriers add a remote-area surcharge for ZIP codes in outlying regions. Knowing the destination ZIP code up front helps you estimate cost more accurately. If you need to work out chargeable weight, try our volumetric weight calculator alongside this tool.

For anyone shipping gifts or personal items to family in the US, getting the ZIP code right helps the driver deliver faster — especially in large cities that span hundreds of different ZIP codes. Learn more in our complete guide to shipping to the USA.

How to use this tool

• 1 Type a city name (e.g. "Houston", "San Jose") to see every ZIP code for that city.
• 2 Enter part of a ZIP code (e.g. "900") to list every code that starts with those digits.
• 3 Enter a two-letter state code (e.g. "TX") or pick a state from the dropdown to narrow the results.
• 4 Click the copy button next to a result to grab the ZIP code quickly when filling out an address or shipping label.

ZIP codes for the most-shipped US states

See a dedicated page for each of our most-shipped destination states, with the full ZIP code table and a quick filter.

Need a US ZIP code to fill out an online form?

Many people search for "US ZIP code" while filling out a sign-up or checkout form. If your goal is an actual shipment or transaction, always use the real ZIP code that matches the recipient's actual US address — that's the only way to guarantee a parcel, invoice, or confirmation arrives correctly.

Gateway Express does not encourage using a fake address or ZIP code to register an account, since this can violate a service's terms of use and cause problems later. If you're preparing to ship something to the US and need to verify a recipient's address, our team is ready to help.

Frequently asked questions

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