Find ZIP+4 for an Address (or Millions of Them)
Look up the full 9-digit ZIP code for a single address for free, or add ZIP+4 to your entire address list in bulk.
Quick Answer
A ZIP+4 code is a 4-digit extension added to a standard 5-digit ZIP code (making a 9-digit "ZIP9"). It narrows delivery down to a specific block, building, or PO box. You can look up the ZIP+4 for any US address using the tool below. For bulk lookups, upload a spreadsheet or use the API.
What Is a ZIP+4 Code?
The USPS assigns ZIP+4 codes to identify small delivery segments: a few houses on a block, a floor of a large building, or an individual high-volume mail recipient. The full 9-digit code looks like 20170-0001, where 20170 is the 5-digit ZIP and 0001 is the +4 extension.
ZIP+4 codes are used for mail presort discounts, address validation, delivery point verification, and regulatory compliance. If you're mailing at bulk rates, your mail house likely needs them.
What Geocodio Returns
When you check the "USPS ZIP+4" box (or use the zip4 API field append), Geocodio returns the ZIP+4 range, full ZIP9, carrier route ID, delivery type, record type, and whether the address is an exact USPS match. You also get a Congressional district indicator and FIPS class code. For the full list of fields, see the ZIP+4 data guide.
How to Look Up ZIP+4 in Bulk
Spreadsheet: Upload a CSV or Excel file with your addresses. Check the box for "USPS ZIP+4" and download the results. Geocodio will add the ZIP+4, carrier route, and delivery indicators to each row.
API: Use the Geocodio API with the zip4 field append. Works for single lookups, batch processing, and the Lists API for large files.
The first 2,500 lookups per day are free. No credit card required. Try a single address below.
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Cost depends on frequency and volume. First 2,500 lookups/day free then $1/1,000. Billed on the 1st of the following month unless you purchase credits.
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Process up to 5 million geocoding and data append lookups per day per dedicated instance
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$5,000 per year with 25,000 lookups/month included. Overage at $2/1,000 — purchased credits don't expire.
$2/1,000 credits after Enterprise Unlimited subscription fee. Purchased credits don't expire.
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API Documentation
Use our API to integrate ZIP+4 appends into an app in real time, for batches, or bulk process CSVs
Complete guide to ZIP codes
Learn what ZIP codes are, how to find your ZIP code, and use Geocodio's lookup tools for accurate address data.
By the time you finish reading this page, the Geocodio API will have processed 5.3 million lookups.
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