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iFrame scaling issues and solutions

Embedding external content via an iFrame is a common technique in web development, for example, to display booking systems, maps, or other web applications. However, this can often lead to layout issues—especially when the height and width are not set correctly. A common mistake is the use of excessive percentages, which results in an oversized and unusable iframe. In this article, we explain why this happens, what the consequences are, and how you can easily solve the issue using a cleaner, responsive approach.

When embedding an iFrame on a website, unexpected scaling issues can occur if percentages are used for height and width. A typical example:



Screenshot 2025-05-28 at 11.12.32

What’s going wrong?

The attributes height="500%" and width="640%" make the iframe five times taller and over six times wider than its parent container. Percentages in HTML and CSS are calculated relative to the parent element. If that container has limited size, the iframe gets massively blown up, resulting in:

  • Scrolling issues

  • Misalignment

  • Loss of responsiveness

  • Poor user experience on mobile devices

  • Scrollproblemen

  • Onverwachte uitlijning

  • Verlies van responsiviteit

The Solution: Fixed or Responsive iFrame

Instead, opt for a fixed height and a responsive width, so the iframe adjusts neatly to the screen size:

 

Screenshot 2025-05-28 at 11.16.18

Explanation of the improved version:

    • width="100%": Adapts to the width of the parent element, ideal for responsive designs.

    • height="600px": Sets a fixed height so the iframe displays content properly without taking up unnecessary space.

    • style="border: none;": Removes the border for a cleaner appearance.

    • frameborder="0": Deprecated, but still useful for ensuring no border appears in older browsers.

    Screenshot 2025-05-28 at 11.23.36

Extra Tips

  • Use CSS for further control, for example with media queries to adjust height on mobile devices.

  • If you want a full-page view, consider using height: 100vh (viewport height) in CSS.

  • Keep in mind that some external websites have security settings (e.g., X-Frame-Options) that prevent them from being embedded in an iframe.