How to Render PDFs with Custom Paper Size in C#

Which Standard Paper Sizes Are Available?

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");

IronPDF supports an extensive collection of standard paper sizes including:

• ISO 216 Series: A0 through A10, B0 through B10
• North American: Letter, Legal, Tabloid, Executive
• Architectural: ANSI A through E
• Japanese: JIS B0 through B10
• Envelope Sizes: Various international envelope standards

For a complete list of available paper sizes and their dimensions, refer to the API Reference documentation.

What Properties Control Paper Size?

• 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.

When using these properties in conjunction with custom margins, you can achieve precise control over your PDF layout.

How Do I Get Standard Paper Sizes in Different 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();

This functionality is particularly useful when integrating with CSS responsive layouts or when you need to calculate exact dimensions for custom layouts.

What Units Can I Use for Custom Dimensions?

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");

Here are additional examples for each measurement unit:

// Example: Custom paper size in inches (for US letter-like custom size)
renderer.RenderingOptions.SetCustomPaperSizeInInches(8.5, 11.5);

// Example: Custom paper size in millimeters (for precise metric measurements)
renderer.RenderingOptions.SetCustomPaperSizeInMillimeters(297, 420); // A3 size

// Example: Custom paper size in pixels (useful for screen-based layouts)
renderer.RenderingOptions.SetCustomPaperSizeInPixelsOrPoints(1024, 768, 96); // 96 DPI

// Example: Custom paper size in inches (for US letter-like custom size)
renderer.RenderingOptions.SetCustomPaperSizeInInches(8.5, 11.5);

// Example: Custom paper size in millimeters (for precise metric measurements)
renderer.RenderingOptions.SetCustomPaperSizeInMillimeters(297, 420); // A3 size

// Example: Custom paper size in pixels (useful for screen-based layouts)
renderer.RenderingOptions.SetCustomPaperSizeInPixelsOrPoints(1024, 768, 96); // 96 DPI

When working with custom sizes, you might also want to explore viewport and zoom settings to ensure your content fits properly within the custom dimensions.

What Parameters Does ExtendPage Accept?

The ExtendPage method accepts the following parameters:

• Page Index: The zero-based index of the page to modify
• Left Extension: Amount to extend/reduce the left side
• Right Extension: Amount to extend/reduce the right side
• Top Extension: Amount to extend/reduce the top side
• Bottom Extension: Amount to extend/reduce the bottom side
• Measurement Unit: The unit of measurement (millimeters, inches, etc.)

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");

Here's a more comprehensive example showing various page modifications:

// Extend all sides equally
pdf.ExtendPage(0, 10, 10, 10, 10, MeasurementUnit.Millimeter);

// Reduce page size (negative values)
pdf.ExtendPage(1, -20, -20, -10, -10, MeasurementUnit.Millimeter);

// Extend only top and bottom (useful for adding header/footer space)
pdf.ExtendPage(2, 0, 0, 25, 25, MeasurementUnit.Millimeter);

// Work with inches instead of millimeters
pdf.ExtendPage(3, 0.5, 0.5, 1, 1, MeasurementUnit.Inch);

// Extend all sides equally
pdf.ExtendPage(0, 10, 10, 10, 10, MeasurementUnit.Millimeter);

// Reduce page size (negative values)
pdf.ExtendPage(1, -20, -20, -10, -10, MeasurementUnit.Millimeter);

// Extend only top and bottom (useful for adding header/footer space)
pdf.ExtendPage(2, 0, 0, 25, 25, MeasurementUnit.Millimeter);

// Work with inches instead of millimeters
pdf.ExtendPage(3, 0.5, 0.5, 1, 1, MeasurementUnit.Inch);