Mail merge is one of the most useful things Microsoft Word can do, and one of the least understood. If you’ve ever needed to send the same letter to dozens of people but with each one addressed personally, or print a sheet of labels from a customer list, mail merge is the tool for the job. It works by combining a Word document (your template) with a data source — usually an Excel spreadsheet — to produce a personalised copy for each row in your data.
What Is Mail Merge and When Should You Use It?
Mail merge creates multiple versions of a document by pulling in data from a list. Each record in your list becomes its own personalised output. Common uses include:
- Personalised letters (invoices, renewal notices, client updates)
- Mailing labels from a contact list
- Envelopes addressed to a list of recipients
- Emails sent from Outlook with personalised content
- Certificates or name badges with individual names
Mail merge saves hours of copying and pasting, and eliminates the risk of leaving the wrong name in a document. Even for 20 or 30 recipients, it’s faster and more reliable than doing it manually.
Step 1: Prepare Your Excel Spreadsheet
Your data source needs to be tidy before you start. Open Excel and make sure your spreadsheet follows these rules:
- Row 1 must be column headers (e.g. FirstName, LastName, Address1, Address2, City, Postcode, Email)
- No blank rows between data rows
- No merged cells
- All data in the first sheet (Sheet1) of the workbook
Keep header names short and without spaces — use FirstName rather than First Name. This makes inserting fields in Word much cleaner. Save and close the spreadsheet before connecting it to Word.
Step 2: Set Up Your Word Document
Open Word and write your letter or document as normal, but leave gaps where the personalised information will go. For example:
Dear [name goes here], We are writing to confirm your renewal date of [date goes here]…
Don’t worry about the exact content yet — you’ll replace those gaps with merge fields shortly. Once your document is laid out, go to the Mailings tab in the ribbon.
Step 3: Connect to Your Data Source
In the Mailings tab, click Select Recipients, then choose Use an Existing List. Navigate to your Excel file and click Open. If Word asks which sheet to use, select the sheet that contains your data (usually Sheet1) and click OK.
Word is now connected to your spreadsheet. You won’t see anything change visually yet, but the Mailings tab controls will become active.
Step 4: Insert Merge Fields
Place your cursor where you want a personalised field to appear — for example, after “Dear “. Then click Insert Merge Field in the Mailings tab. A dropdown will appear showing all the column headers from your spreadsheet. Click the field you want to insert.
Word inserts the field like this: «FirstName». The double chevrons tell you it’s a merge field, not ordinary text. Continue placing your cursor at each gap in your document and inserting the relevant field.
For a standard letter opening, you might end up with:
Dear «FirstName» «LastName»,
You can insert the same field more than once if needed — for example, using «FirstName» in the greeting and again in the body of the letter.
Step 5: Preview Your Results
Before printing or sending anything, click Preview Results in the Mailings tab. Word replaces the field codes with actual data from your first record. Use the arrow buttons to step through each recipient and check everything looks right.
Check for:
- Spacing issues (two spaces between fields, or no space at all)
- Punctuation problems (a comma after a name that sometimes has two parts, sometimes one)
- Dates or numbers displaying in an unexpected format
Click Preview Results again to toggle back to field code view if you need to make edits.
Step 6: Filter or Sort Your Recipients (Optional)
If you only want to send to some of your list, click Edit Recipient List in the Mailings tab. You can uncheck individual rows, or use the Filter option to only include records that meet certain criteria — for example, only people in a specific city, or only contacts with a renewal date this month.
Step 7: Complete the Merge
When you’re happy with the preview, click Finish & Merge in the Mailings tab. You have three options:
- Edit Individual Documents — creates a single Word document with each merged letter on a separate page. Good for reviewing before printing, or for adding individual notes to specific letters.
- Print Documents — sends directly to your printer.
- Send Email Messages — sends via Outlook, using a field from your spreadsheet as the email address. You’ll be asked to specify which column contains the email address and what the subject line should be.
For most letter merges, choose Edit Individual Documents first. This gives you a chance to spot any issues before committing to print.
Creating Labels with Mail Merge
To print address labels, start a new document and go to Mailings > Start Mail Merge > Labels. Select your label brand and product number (this is printed on the label packaging — Avery L7160 is a common A4 sheet). Word sets up a grid matching your label layout.
Connect to your data source as before, then insert address fields into the first label only. Click Update Labels to copy that layout to all the other labels on the sheet. Preview and complete the merge as normal.
Common Mail Merge Errors and How to Fix Them
Field Codes Showing Instead of Data
If your document shows { MERGEFIELD FirstName } instead of the actual name, press Alt + F9 to toggle field code display off. This is a global setting in Word that sometimes gets switched on accidentally.
Dates Showing as a Number
Excel stores dates as serial numbers, and Word sometimes displays them that way. If your date field shows something like 45678 instead of 01/04/2025, you need to add a date format switch to the field. Right-click the merge field, choose Toggle Field Codes, and you’ll see something like { MERGEFIELD RenewalDate }. Edit it to read { MERGEFIELD RenewalDate \@ "dd/MM/yyyy" }, then press F9 to update. Press Alt + F9 to return to normal view.
Numbers Losing Decimal Places or Currency Formatting
Similar issue — Excel formats numbers visually, but Word receives the raw value. Add a numeric picture switch: { MERGEFIELD Amount \# "£#,##0.00" } to display the number as currency. The \# switch controls number formatting, just as \@ controls date formatting.
Extra Blank Lines When a Field Is Empty
If some records have an Address2 line and some don’t, you might get a blank line in letters where Address2 is empty. The fix is to select the entire line containing that field (including the paragraph mark at the end) and use a Word rule. Go to Mailings > Rules > If…Then…Else and set it to skip the line when that field is blank. This is a slightly advanced step but makes a real difference to the finished output.
Tips for Cleaner Mail Merges
- Always keep a backup of the original template before merging — once merged, individual edits are tedious to undo
- Test with a small subset first (filter to 3–5 records) before running the full list
- If your data has inconsistent capitalisation, fix it in Excel first — Word has limited text transformation options
- Save the merged document as a PDF before printing to avoid layout surprises
