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How to Convert Microsoft Word to PDF in C#

Chaknith Bin

Updated:July 28, 2025

A DOCX file is a document created in Microsoft Word, a word processing program within the Microsoft office suited provided by Microsoft. It uses the Office Open XML (OOXML) standard, making it efficient and compatible with various software. It's the default format for Word documents since Word 2007, replacing the older DOC format when its was originally published.

IronPDF has the ability to convert word documents to PDF files in an instance, along with providing a Mail Merge feature for generating personalized batches of documents for individual recipients. Converting from DOCX to PDF ensures universal compatibility, preserves formatting, and adds a layer of security.

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Convert DOCX file to PDF Example

IronPDF allows for developers to convert word documents to pdf programmatically, streamlining efficiency and allowing them to integrate into existing .NET applications or any cross platform .NET framework applications they might have.

The conversion process to convert a Microsoft Word file to PDF format is simple. We first instantiate the DocxToPdfRenderer class. Utilize the RenderDocxAsPdf method of the DocxToPdfRenderer object by providing the filepath of the DOCX file. This method returns a PdfDocument object, allowing you to customize the PDF further. You can download the Modern Chronological Resume DOCX example file.

Microsoft Word Preview

Code Sample

Additionally, the RenderDocxAsPdf method also accepts DOCX data as bytes and streams.

:path=/static-assets/pdf/content-code-examples/how-to/docx-to-pdf-from-file.cs

using IronPdf;

// Instantiate Renderer
DocxToPdfRenderer renderer = new DocxToPdfRenderer();

// Render from DOCX file
PdfDocument pdf = renderer.RenderDocxAsPdf("Modern-chronological-resume.docx");

// Save the PDF
pdf.SaveAs("pdfFromDocx.pdf");

Imports IronPdf

' Instantiate Renderer
Private renderer As New DocxToPdfRenderer()

' Render from DOCX file
Private pdf As PdfDocument = renderer.RenderDocxAsPdf("Modern-chronological-resume.docx")

' Save the PDF
pdf.SaveAs("pdfFromDocx.pdf")

Output PDF

Mail Merge Example

Mail Merge, located on the "Mailings" tab in Microsoft Word, allows you to create a batch of documents with personalized information for each recipient or data entry. It's often used to generate personalized letters, envelopes, labels, or email messages, such as invitations, newsletters, or form letters, where much of the content is the same, but certain details vary for each recipient.

Model

First, let's create a model to store the information that will be mail-merged into its corresponding placeholder.

:path=/static-assets/pdf/content-code-examples/how-to/docx-to-pdf-mail-merge-model.cs

internal class RecipientsDataModel
{
    public string Date { get; set; }
    public string Location{ get; set; }
    public string Recipients_Name { get; set; }
    public string Contact_Us { get; set; }
}

Friend Class RecipientsDataModel
	Public Property [Date]() As String
	Public Property Location() As String
	Public Property Recipients_Name() As String
	Public Property Contact_Us() As String
End Class

I have modified a template provided by Microsoft Word for our purposes. Please download the Party Invitation DOTX example file. For our use case, let's set the MailMergePrintAllInOnePdfDocument property to true, which combines the PDFs into a single PdfDocument object. The merge fields that we are going to use are Date, Location, Recipient's Name, and Contact Us.

Microsoft Word Preview

Code Sample

:path=/static-assets/pdf/content-code-examples/how-to/docx-to-pdf-mail-merge.cs

using IronPdf;
using System.Collections.Generic;
using System.Linq;

var recipients = new List<RecipientsDataModel>()
    {
        new RecipientsDataModel()
        {
            Date ="Saturday, October 15th, 2023",
            Location="Iron Software Cafe, Chiang Mai",
            Recipients_Name="Olivia Smith",
            Contact_Us = "support@ironsoftware.com"
        },
        new RecipientsDataModel()
        {
            Date ="Saturday, October 15th, 2023",
            Location="Iron Software Cafe, Chiang Mai",
            Recipients_Name="Ethan Davis",
            Contact_Us = "support@ironsoftware.com"
        },
    };

DocxToPdfRenderer docxToPdfRenderer = new DocxToPdfRenderer();

// Apply render options
DocxPdfRenderOptions options = new DocxPdfRenderOptions();

// Configure the output PDF to be combined into a single PDF document
options.MailMergePrintAllInOnePdfDocument = true;

// Convert DOTX to PDF
var pdfs = docxToPdfRenderer.RenderDocxMailMergeAsPdf<RecipientsDataModel>(
     recipients,
     "Party-invitation.dotx",
     options);

pdfs.First().SaveAs("mailMerge.pdf");

Imports IronPdf
Imports System.Collections.Generic
Imports System.Linq

Private recipients = New List(Of RecipientsDataModel)() From {
	New RecipientsDataModel() With {
		.Date ="Saturday, October 15th, 2023",
		.Location="Iron Software Cafe, Chiang Mai",
		.Recipients_Name="Olivia Smith",
		.Contact_Us = "support@ironsoftware.com"
	},
	New RecipientsDataModel() With {
		.Date ="Saturday, October 15th, 2023",
		.Location="Iron Software Cafe, Chiang Mai",
		.Recipients_Name="Ethan Davis",
		.Contact_Us = "support@ironsoftware.com"
	}
}

Private docxToPdfRenderer As New DocxToPdfRenderer()

' Apply render options
Private options As New DocxPdfRenderOptions()

' Configure the output PDF to be combined into a single PDF document
options.MailMergePrintAllInOnePdfDocument = True

' Convert DOTX to PDF
Dim pdfs = docxToPdfRenderer.RenderDocxMailMergeAsPdf(Of RecipientsDataModel)(recipients, "Party-invitation.dotx", options)

pdfs.First().SaveAs("mailMerge.pdf")

Output PDF

Once the PDF document is created, you have the flexibility to make additional changes. These include exporting it as PDF/A or PDF/UA, as well as adding a digital certificate. You can also manipulate individual pages by merging or splitting PDFs, rotating them, and you have the option to apply annotations and bookmarks.

Aside from those features, IronPDF also supports converting to other document formats. For additional information regarding the other functionality that IronPDF has to offer, please refer to this tutorial.

Chaknith Bin

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Software Engineer

Chaknith is the Sherlock Holmes of developers. It first occurred to him he might have a future in software engineering, when he was doing code challenges for fun. His focus is on IronXL and IronBarcode, but he takes pride in helping customers with every product. Chaknith leverages his knowledge from talking directly with customers, to help further improve the products themselves. His anecdotal feedback goes beyond Jira tickets and supports product development, documentation and marketing, to improve customer’s overall experience.When he isn’t in the office, he can be found learning about machine learning, coding and hiking.

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Jeffrey T. Fritz

Principal Program Manager - .NET Community Team

Jeff is also a Principal Program Manager for the .NET and Visual Studio teams. He is the executive producer of the .NET Conf virtual conference series and hosts 'Fritz and Friends' a live stream for developers that airs twice weekly where he talks tech and writes code together with viewers. Jeff writes workshops, presentations, and plans content for the largest Microsoft developer events including Microsoft Build, Microsoft Ignite, .NET Conf, and the Microsoft MVP Summit

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