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ZIP Code Leading Zero Fixer
CRM Import-Ready Contact Cleanup
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Open a contact list in Excel and a ZIP code like 02134 can quietly become 2134. Import that file into a CRM and those contacts now have a four-digit ZIP that matches nothing. Load your file below to put the zeros back. The fix runs in your browser and nothing is uploaded.
ZIP code leading zero fixer
Paste ZIP codes one per line, or upload a CSV and name the ZIP column. Codes that lost their leading zeros in a spreadsheet (2134 instead of 02134) are padded back to five digits, nine-digit codes are written as ZIP+4 (12345-6789), and values that cannot be a US ZIP code are flagged.
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Why the zeros disappear
Microsoft's support article says Excel automatically removes leading zeros from data such as postal codes, and converts large numbers to scientific notation, so that formulas and math operations work on them (source: https://support.microsoft.com/en-us/office/keeping-leading-zeros-and-large-numbers-1bf7b935-36e1-4985-842f-5dfa51f85fe7). A ZIP code is a code, not a number, so this changes your data. Microsoft also notes that applying a format afterwards will not restore leading zeros that were already removed (source: https://support.microsoft.com/en-us/office/keeping-leading-zeros-and-large-numbers-1bf7b935-36e1-4985-842f-5dfa51f85fe7). You need to rebuild the values, which is what this tool does.
What the fixer does
- Pads 3- and 4-digit values back to five digits: 2134 becomes 02134, 501 becomes 00501.
- Writes 9-digit values as ZIP+4, for example 021341234 becomes 02134-1234, and pads 7- or 8-digit ones first. Untick the box to keep only the first five digits.
- Removes a trailing ".0" left by spreadsheet exports, and spaces.
- Flags anything with letters (such as Canadian or UK postcodes) or the wrong length, and leaves it unchanged.
- Adds a
zip_checkcolumn noting each change.
USPS Publication 28 describes the last line of an address as the city, state and Five-Digit ZIP Code or ZIP+4 Code (source: https://pe.usps.com/text/pub28/28apb.htm), which is why the tool outputs five digits, or five plus four.
Keep the zeros next time
Microsoft's article describes a few ways to keep leading zeros (source: https://support.microsoft.com/en-us/office/keeping-leading-zeros-and-large-numbers-1bf7b935-36e1-4985-842f-5dfa51f85fe7):
- Import the CSV with Data, From Text/CSV and set the ZIP column's data type to Text.
- Use a custom number format of 00000 for five-digit postal codes, or the Special, Zip Code format.
- Use a helper column with =TEXT(A1,"00000").
Microsoft also describes an Automatic Data Conversions setting in recent Excel versions that can turn off the removal of leading zeros (source: https://support.microsoft.com/en-us/office/keeping-leading-zeros-and-large-numbers-1bf7b935-36e1-4985-842f-5dfa51f85fe7).
Be careful with non-US rows
If your list mixes countries, a 4-digit value might be a valid postcode somewhere else. Filter to US rows before you run the fixer, or check the rows marked "leading zero restored" against the country column.
FAQ
Which column does it use?
The column you name, or the first column with "zip" or "postal" in its header.
Is my file uploaded?
No. The file is read by JavaScript in your browser. Nothing is sent to us or anyone else, and nothing is kept after you close the tab.
If you want the whole file cleaned
Our CRM Import-Ready Contact Cleanup fixes names, emails, phones, states, ZIP codes and duplicates across the whole file and returns an import-ready CSV for $9 per 500 rows. We are independent and not affiliated with any CRM vendor.
Buy CRM cleanup - $9 per 500 rows
CRM Import-Ready Contact Cleanup
Want the whole file cleaned? We fix emails, phones, names and duplicates and return an import-ready CSV. $9 per 500 rows.