What each status means
- Reference match: the five-digit code exists in the GeoNames postal dataset and the row shows its recorded place.
- No reference match: the format is valid but the code is not in the dataset. That does not prove the ZIP is unassigned; verify it with USPS.
- Invalid five-digit format: the value is not exactly five digits. ZIP+4 values are accepted when written as 02108-1234; only the first five digits are looked up.
Tips for spreadsheets
Leading zeros disappear when a spreadsheet treats ZIP codes as numbers, so 02108 becomes 2108 and will not match. Format the column as text before pasting, or restore the zeros with a formula. Our guides on ZIP code lookup in Excel and Google Sheets walk through it.