Why Word Mail Merge Inserts Comma in Number Fields From English Locale

When you run a mail merge in Word that pulls number fields from an English locale data source, the merged document often shows a comma in thousands positions. This happens even when the source data displays the number as a plain integer without any comma. The cause is a mismatch between how Word interprets the number format from the data source and the regional settings on your system. This article explains why Word inserts the comma and provides two methods to remove it from the merged output.

Why Word Adds a Comma to Numbers During Mail Merge

Word does not treat number fields as raw text during a mail merge. Instead, it reads the number from the data source and then applies the formatting rules defined by the locale of the data source connection. When the data source is set to an English locale such as English United States, Word interprets the number and formats it with a comma as the thousands separator. This happens regardless of whether the original number in the data source has a comma or not.

The root cause is the numeric picture switch that Word assigns to the merge field by default. When you insert a merge field for a number field, Word may not include any explicit picture switch. In that case, Word falls back to the regional format of the data source locale. If the data source locale uses a comma as the thousands separator, the merged result shows that comma.

A second contributing factor is the locale mismatch between the data source and the target document. For example, if your data source is an Excel file saved with English United States locale and your Word document uses a different locale, Word still applies the data source locale to the number formatting. This mismatch causes unexpected formatting including the comma.

How to Remove the Comma From Mail Merge Number Fields

You have two methods to stop Word from inserting a comma in number fields. Method 1 uses the numeric picture switch inside the merge field code. Method 2 changes the locale of the data source connection in Word. Use Method 1 for a quick fix on a single field. Use Method 2 if you have many number fields and want to apply the fix globally.

Method 1: Add a Numeric Picture Switch to the Merge Field

1. Open the mail merge main document in Word
   Make sure the document contains the merge fields you inserted earlier. Do not start the merge yet.
2. Press Alt+F9 to show field codes
   Each merge field changes from a placeholder like { MERGEFIELD Amount } to its field code representation. The braces are the actual field code braces, not typed characters.
3. Locate the merge field that shows the comma
   Find the field code for the number field. It will look similar to { MERGEFIELD Amount } with no formatting switch.
4. Add a numeric picture switch to the field code
   Type \# 0 after the field name but before the closing brace. The field code becomes { MERGEFIELD Amount \# 0 }. This switch tells Word to display the number as a whole number with no comma and no decimal places.
5. Press Alt+F9 again to hide field codes
   The field returns to showing the placeholder name. The switch is now part of the field.
6. Preview the merge result
   Click Preview Results in the Mailings tab. The number should now appear without the comma. If the number has decimals and you want to show them, use \# 0.00 instead.

Method 2: Change the Data Source Locale in Word

1. Open the mail merge main document in Word
   Ensure the document is connected to the data source that causes the comma issue.
2. Go to File > Options > Advanced
   Scroll down to the General section.
3. Click the File Locations button
   This opens the File Locations dialog where you see the current data source path.
4. Close the File Locations dialog without making changes
   This step forces Word to refresh the connection to the data source. The actual locale change happens in the next step.
5. In the Mailings tab, click Select Recipients > Use an Existing List
   Re-select the same data source file. Word now re-reads the file and prompts you to choose the table or sheet.
6. Click the Data Source Settings button if available
   In older versions of Word, a dialog appears with a Data Source Settings button. Click it and change the locale to match your document locale. In Word 365, this option may be absent. If absent, proceed to the next step.
7. Edit the data source in Excel and save with the target locale
   Open the data source file in Excel. Go to File > Options > Advanced and set the Default locale for data source to the locale that does not use a comma as a thousands separator, such as English United Kingdom. Save the file. Reconnect Word to the file.

If the Comma Still Appears After the Main Fix

Word Still Shows a Comma After Adding the Numeric Picture Switch

The numeric picture switch \# 0 forces Word to display the number as an integer with no commas. If the comma persists, check that you typed the switch correctly. The backslash must be included and there must be a space between the field name and the backslash. Also ensure you pressed Alt+F9 to update the field code and then F9 to update the field after adding the switch.

Number Appears With a Comma Only in the Preview but Not in the Final Merge

This is a display issue in the preview pane. The preview uses the current locale of the Word session, which may differ from the locale used during the actual merge. To confirm, complete the merge to a new document by clicking Finish & Merge > Edit Individual Documents. The final output should follow the numeric picture switch you set.

Merge Field Shows the Field Code Instead of the Number

If you see { MERGEFIELD Amount \# 0 } in the final merged document, you have toggled field codes on globally. Press Alt+F9 to turn off field code display. Then update the fields by selecting the entire document and pressing F9.

Mail Merge Number Display: Numeric Picture Switch vs Locale Change

Item	Numeric Picture Switch	Data Source Locale Change
Scope	Single field at a time	All number fields in the merge
Setup time	Under one minute per field	Several minutes plus Excel edit
Risk of side effects	None	May affect date and currency formatting
Requires field code editing	Yes	No
Works with decimals	Yes, with \# 0.00	Yes, but locale controls decimal symbol

Use the numeric picture switch for a quick fix on one or two fields. Use the locale change when you have many number fields and want consistent formatting across the entire merge.

You can now prevent Word from inserting a comma in mail merge number fields by adding a numeric picture switch or adjusting the data source locale. For a single field, the switch \# 0 is the fastest solution. For a large merge with many number fields, changing the data source locale in Excel saves time. If you work with international data sources, consider using the \# #,##0 switch to display commas intentionally when needed.