Fixing Font Kerning Issues in IronPDF

Updated:June 22, 2025

This issue specifically affects the WebKit version (<= 2021.3.1) of our library. Font kerning issues with system fonts such as Arial and Arial Bold are caused by faulty kerning within the Windows system fonts. To address this issue, we recommend transitioning to a later version of IronPDF. Starting from version (>= 2021.9.3678), we introduced Chrome Engine rendering, which offers improved compatibility and resolves these font kerning issues.

Workaround

To workaround the font kerning problem, please remove the system font and download a new font (such as ArialMT) from an online resource. Then, link this font into the HTML using @font-face:

@font-face {
    /* Define a new font family for ArialMT Regular */
    font-family: 'ArialMT Regular'; 
    font-style: normal; 
    font-weight: normal; 
    /* Specify the local source and the WOFF format for the font */
    src: local('ArialMT Regular'), url('arialmt.woff') format('woff'); 
}

Next, replace any font-family: Arial; declaration in your HTML with font-family: ArialMT Regular;, and then render the PDF. This change ensures that the web font is used instead of the potentially problematic system font, thereby avoiding kerning issues caused by the system's default fonts.

Chaknith Bin

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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.