IronPDF How-Tos Custom Paper Size How to Render PDFs with Custom Paper Size Chaknith Bin Updated:August 14, 2025 A custom paper size refers to a non-standard paper size that is defined by the user rather than being a standard size like A4 or letter size (8.5 x 11 inches). Custom paper sizes are often used when printing documents that require a unique or specific layout, such as posters, banners, or specialty documents. Discover the extensive range of paper sizes available with IronPDF, offering a wide selection to suit your needs! Get started making PDFs with NuGet now: Install IronPDF with NuGet Package Manager PM > Install-Package IronPdf Copy and run this code snippet. new IronPdf.ChromePdfRenderer { RenderingOptions = { PaperSize = IronPdf.Rendering.PdfPaperSize.Custom, } } .RenderHtmlAsPdf("<h1>Custom size</h1>") .Renderer.RenderingOptions.SetCustomPaperSizeInInches(5, 7) .SaveAs("custom‑size.pdf"); Deploy to test on your live environment Start using IronPDF in your project today with a free trial Free 30 day Trial How to Render PDFs with Custom Paper Size Download IronPDF from NuGet for setting custom paper sizes in PDFs Instantiate the ChromePdfRenderer class in C# Access the RenderingOptions on the new object Invoke one of the SetCustomPaperSize methods based on the measurement unit Render and export the PDF document Start using IronPDF in your project today with a free trial. First Step: Start for Free Use Standard Paper Size Example First, create an instance of the ChromePdfRenderer class. Then, use the RenderingOptions property of the newly created object to modify the PaperSize. Set it to one of the predefined values from the PdfPaperSize enum to specify the desired paper size. We offer over 100 predefined standard paper sizes for your convenience. Code Below is an example of how to set a standard paper size: :path=/static-assets/pdf/content-code-examples/how-to/custom-paper-size-standard-paper-size.cs using IronPdf; using IronPdf.Rendering; ChromePdfRenderer renderer = new ChromePdfRenderer(); // Set paper size to A4 renderer.RenderingOptions.PaperSize = PdfPaperSize.A4; PdfDocument pdf = renderer.RenderHtmlAsPdf("<h1>Standard Paper Size</h1>"); pdf.SaveAs("standardPaperSize.pdf"); Imports IronPdf Imports IronPdf.Rendering Private renderer As New ChromePdfRenderer() ' Set paper size to A4 renderer.RenderingOptions.PaperSize = PdfPaperSize.A4 Dim pdf As PdfDocument = renderer.RenderHtmlAsPdf("<h1>Standard Paper Size</h1>") pdf.SaveAs("standardPaperSize.pdf") $vbLabelText $csharpLabel Related Properties PaperSize: Set an output paper size for PDF pages with predefined sizes such as letter, A3, A4, etc. ForcePaperSize: Forces page sizes to be exactly what is specified via IronPdf.ChromePdfRenderOptions.PaperSize by resizing the page after generating a PDF from HTML. This feature is useful for bypassing CSS rules that specify paper size. Get Standard Paper Sizes in Various Units Need to find the dimensions of standard paper sizes? You can easily do so using the ToMillimeters method. This method returns a tuple containing the width and height of the standard paper size as Length objects. The Length class is incredibly versatile, allowing you to effortlessly convert these dimensions into a variety of units, including: Millimeters Centimeters Inches Pixels Points :path=/static-assets/pdf/content-code-examples/how-to/custom-paper-size-standard-paper-size-in-other-unit.cs using IronPdf.Rendering; double A4WidthInPixel = PdfPaperSize.A4.ToMillimeters().width.ToPixel(); double A4HeightInCentimeter = PdfPaperSize.A4.ToMillimeters().height.ToCentimeter(); Imports IronPdf.Rendering Private A4WidthInPixel As Double = PdfPaperSize.A4.ToMillimeters().width.ToPixel() Private A4HeightInCentimeter As Double = PdfPaperSize.A4.ToMillimeters().height.ToCentimeter() $vbLabelText $csharpLabel Use Custom Paper Size Example First, we begin by instantiating the ChromePdfRenderer class. From the newly created object, we can access the RenderingOptions to apply a custom paper size to the newly generated PDF document. There are four methods that can be used to set the output paper size for PDF pages, each based on a different measurement unit: SetCustomPaperSizeInCentimeters: Dimensions are in centimeters. SetCustomPaperSizeInInches: Dimensions are in inches. SetCustomPaperSizeInMillimeters: Dimensions are in millimeters. SetCustomPaperSizeInPixelsOrPoints: Dimensions are in pixels or points. Code Below is an example of how to set a custom paper size in centimeters: :path=/static-assets/pdf/content-code-examples/how-to/custom-paper-size-cm.cs using IronPdf; ChromePdfRenderer renderer = new ChromePdfRenderer(); // Set custom paper size in cm renderer.RenderingOptions.SetCustomPaperSizeinCentimeters(15, 15); PdfDocument pdf = renderer.RenderHtmlAsPdf("<h1>Custom Paper Size</h1>"); pdf.SaveAs("customPaperSize.pdf"); Imports IronPdf Private renderer As New ChromePdfRenderer() ' Set custom paper size in cm renderer.RenderingOptions.SetCustomPaperSizeinCentimeters(15, 15) Dim pdf As PdfDocument = renderer.RenderHtmlAsPdf("<h1>Custom Paper Size</h1>") pdf.SaveAs("customPaperSize.pdf") $vbLabelText $csharpLabel Output PDF Modify Paper Dimension Example In an existing PDF document or a freshly rendered PDF, the size of each page can be modified using the ExtendPage method. This method allows you to specify the target page index, the values to modify each of the four sides, and the units of measurement. The values for each side can be negative, which will reduce that particular side, or positive, which will extend that side. Code Below is an example of how to modify paper dimensions: :path=/static-assets/pdf/content-code-examples/how-to/custom-paper-size-modify-paper-size.cs using IronPdf; using IronPdf.Editing; PdfDocument pdf = PdfDocument.FromFile("customPaperSize.pdf"); pdf.ExtendPage(0, 50, 0, 0, 0, MeasurementUnit.Millimeter); pdf.SaveAs( "extendedLeftSide.pdf"); Imports IronPdf Imports IronPdf.Editing Private pdf As PdfDocument = PdfDocument.FromFile("customPaperSize.pdf") pdf.ExtendPage(0, 50, 0, 0, 0, MeasurementUnit.Millimeter) pdf.SaveAs("extendedLeftSide.pdf") $vbLabelText $csharpLabel Output PDF Ready to see what else you can do? Check out our tutorial page here: Create PDFs Frequently Asked Questions How can I render a PDF with a custom paper size in C#? To render a PDF with a custom paper size using IronPDF, instantiate the ChromePdfRenderer class, access the RenderingOptions, and use one of the SetCustomPaperSize methods based on the measurement unit you prefer, such as centimeters or inches. What are the steps to download the library for custom paper size settings? You can download IronPDF via NuGet to access features for setting custom paper sizes in PDFs. This library provides the tools needed to define specific dimensions for your PDF documents. How do I apply a standard paper size in PDF generation? In IronPDF, create an instance of ChromePdfRenderer, then use the RenderingOptions to set the PaperSize property to a predefined value from the PdfPaperSize enum, such as A4 or letter size. Is it possible to modify the page size of an existing PDF using IronPDF? Yes, IronPDF allows you to modify the page size of an existing PDF by using the ExtendPage method. This method enables you to adjust the dimensions of each side of the page by specifying the page index and measurement units. What are the options for setting custom paper sizes in IronPDF? IronPDF provides methods to set custom paper sizes using various measurement units: SetCustomPaperSizeInCentimeters, SetCustomPaperSizeInInches, SetCustomPaperSizeInMillimeters, and SetCustomPaperSizeInPixelsOrPoints. How does the ForcePaperSize feature work in PDF rendering? The ForcePaperSize feature in IronPDF ensures that the actual page sizes match the specified dimensions by resizing the page after rendering the PDF from HTML. This helps to override any CSS rules that define paper size. What predefined paper sizes are available in IronPDF? IronPDF offers over 100 predefined paper sizes, including common sizes like A3, A4, and letter size, which can be selected via the PdfPaperSize enum. How can I convert standard paper sizes into different units using IronPDF? You can use IronPDF's ToMillimeters method to convert standard paper sizes into various units such as millimeters, centimeters, inches, pixels, or points, providing flexibility in PDF design. Chaknith Bin Chat with engineering team now Software Engineer Chaknith works on IronXL and IronBarcode. He has deep expertise in C# and .NET, helping improve the software and support customers. His insights from user interactions contribute to better products, documentation, and overall experience. Ready to Get Started? Free NuGet Download Total downloads: 15,316,769 View Licenses