Converting HTML to PDF is common—from invoices to reports—but the default settings rarely match your brand and print needs. With Aspose.HTML for .NET, you can precisely control page size, margins, orientation, and CSS media rules to produce consistent, professional PDFs. This guide shows a clean, repeatable setup and includes a complete C# sample.

Key Takeaways

  • Use Converter.ConvertHTML with PdfSaveOptions for robust HTML → PDF conversion.
  • Configure PageSetup.AnyPage to set size and margins (A4/A3/custom); choose portrait or landscape by size.
  • Apply options.Css.MediaType (Print vs Screen) to honor the right CSS.
  • Generate multiple variants (e.g., A4 portrait + A3 landscape) from the same HTML for different audiences.

Step‑by‑Step Guide

1) Set up the project

Install the NuGet package and create a console project (steps in How to run).

2) Load HTML content

Load an existing file or build an HTMLDocument from a string. Provide a base URI to resolve relative CSS, images, and fonts.

3) Configure page geometry and media

Use PdfSaveOptions.PageSetup.AnyPage to define Size and Margin, and set Css.MediaType to target @media print rules when needed.

4) Convert to PDF

Call Converter.ConvertHTML(document, options, path) to write the PDF file.

Complete Example (Compilable C#)

using System;
using System.IO;
using Aspose.Html;
using Aspose.Html.Converters;
using Aspose.Html.Saving;            // PdfSaveOptions
using Aspose.Html.Rendering;         // MediaType
using Aspose.Html.Drawing;           // Length, Size, Margin, Page

namespace HtmlToPdfCustomization
{
    internal static class Program
    {
        // How to run:
        // 1) dotnet new console -n HtmlToPdfCustomization
        // 2) cd HtmlToPdfCustomization
        // 3) dotnet add package Aspose.HTML
        // 4) Replace Program.cs with this file's contents
        // 5) dotnet run -- "path-to-input.html"   (optional)
        private static void Main(string[] args)
        {
            string outDir = Path.Combine(Directory.GetCurrentDirectory(), "out");
            Directory.CreateDirectory(outDir);

            // Load HTML from file if provided; otherwise, use inline HTML
            HTMLDocument document;
            if (args.Length > 0 && File.Exists(args[0]))
            {
                document = new HTMLDocument(args[0]);
            }
            else
            {
                string html = "<!DOCTYPE html>" +
                              "<html><head><meta charset=\\\"utf-8\\\">" +
                              "<title>HTML to PDF (Aspose.HTML)</title>" +
                              "<style>body{font-family:Arial,Helvetica,sans-serif;margin:24px}" +
                              ".lead{color:#444} table{width:100%;border-collapse:collapse}" +
                              "th,td{border:1px solid #ddd;padding:6px 8px;text-align:left}" +
                              "@media print{body{font-size:12pt}.lead{color:#000}}</style>" +
                              "</head><body>" +
                              "<h1>Order Summary</h1>" +
                              "<p class=\\\"lead\\\">This PDF respects print CSS and custom page settings.</p>" +
                              "<table><tr><th>Item</th><th>Qty</th><th>Price</th></tr>" +
                              "<tr><td>Widget A</td><td>3</td><td>$12.00</td></tr>" +
                              "<tr><td>Widget B</td><td>2</td><td>$9.50</td></tr></table>" +
                              "</body></html>";
                document = new HTMLDocument(html, ".");
            }

            using (document)
            {
                var mm = Length.FromMillimeters;

                // Variant 1: A4 portrait with 12.7 mm margins, using print CSS
                var a4 = new PdfSaveOptions();
                a4.Css.MediaType = MediaType.Print;
                a4.PageSetup.AnyPage = new Page(
                    new Size(mm(210), mm(297)), // A4
                    new Margin(mm(12.7), mm(12.7), mm(12.7), mm(12.7))
                );
                string a4Path = Path.Combine(outDir, "order-a4.pdf");
                Converter.ConvertHTML(document, a4, a4Path);
                Console.WriteLine($"Saved: {a4Path}");

                // Variant 2: A3 landscape with tighter margins, using screen CSS
                var a3Landscape = new PdfSaveOptions();
                a3Landscape.Css.MediaType = MediaType.Screen;
                a3Landscape.PageSetup.AnyPage = new Page(
                    new Size(mm(420), mm(297)), // A3 landscape
                    new Margin(mm(10), mm(10), mm(10), mm(10))
                );
                string a3Path = Path.Combine(outDir, "order-a3-landscape.pdf");
                Converter.ConvertHTML(document, a3Landscape, a3Path);
                Console.WriteLine($"Saved: {a3Path}");

                // Variant 3: Custom 6 x 9 inches trim with narrow margins (print CSS)
                var custom = new PdfSaveOptions();
                custom.Css.MediaType = MediaType.Print;
                custom.PageSetup.AnyPage = new Page(
                    new Size(Length.FromInches(6), Length.FromInches(9)),
                    new Margin(mm(5), mm(5), mm(5), mm(5))
                );
                string customPath = Path.Combine(outDir, "order-6x9.pdf");
                Converter.ConvertHTML(document, custom, customPath);
                Console.WriteLine($"Saved: {customPath}");
            }
        }
    }
}

What this code does

  • Loads HTML from a file or in-memory string with a base URI.
  • Configures PdfSaveOptions for A4 portrait, A3 landscape, and a custom 6×9 inch trim size.
  • Applies MediaType.Print or MediaType.Screen to match your CSS rules.
  • Exports three tailored PDFs into an out/ folder.

Troubleshooting & Tips

  • Wrong styles: toggle options.Css.MediaType between Print and Screen to match your stylesheet.
  • Clipped content: increase page size or margins; wider formats help for large tables.
  • Missing fonts: ensure fonts are available to the renderer or embed via @font-face.
  • Performance: simplify heavy DOM/CSS; prefer cached static assets.

FAQ

Q1. How do I set page size and margins? Use PdfSaveOptions.PageSetup.AnyPage = new Page(Size, Margin) with units from Length (millimeters or inches).

Q2. Can I force print styles? Yes. Set options.Css.MediaType = MediaType.Print so @media print rules apply.

Q3. How do I render landscape pages? Provide a landscape Size (e.g., A3 420 × 297 mm) when creating the Page.

Q4. Can I export multiple variants from one HTML? Create separate PdfSaveOptions objects (different Css.MediaType and sizes) and call Converter.ConvertHTML for each.

Q5. Do I need a browser engine installed? No. Aspose.HTML renders server‑side without external browsers.

Conclusion

Using PdfSaveOptions and media‑aware CSS, you can create polished PDFs tailored to print, archival, or executive needs. Start with A4 portrait for general documents, add A3 landscape for wide layouts, and keep a custom trim size for booklets or reports.

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