Layout shift refers to the unexpected movement of content on a webpage while it's loading or during user interaction. It happens when visible elements like text, images, buttons, or ads suddenly move positions, often caused by late-loading resources or changes in fonts and media dimensions.

This issue directly impacts the user experience. For example, a user might try to click a button, but if the content shifts, they could accidentally click something else—leading to frustration or confusion. This is especially important for mobile users, where screen space is limited and layout stability is key.

Google’s Core Web Vitals includes a metric called CLS (Cumulative Layout Shift), which scores how often and how much elements move around. A low CLS score means your page is stable as it loads and is more likely to provide a smooth user experience. Good layout stability not only helps your visitors, but it also positively affects your SEO rankings.

To reduce layout shift, web designers and developers often set fixed dimensions on images and videos, preload fonts, and avoid inserting dynamic content above existing content. If you're using a website builder, it may include built-in tools to help minimize layout shifts automatically.

Why layout shift matters for your website

Even if your website looks visually appealing, unexpected movement can degrade trust and usability. Visitors may leave your site if they feel it's unstable or difficult to use. Especially in ecommerce, layout shifts can hurt conversions if a customer accidentally clicks the wrong button or loses track of where they were. Platforms like B12 aim to help businesses create polished sites that minimize these types of issues.

How to fix or prevent layout shift

Reserve space for elements

When you include images, ads, or embedded videos, always specify their height and width. This way, the browser can allocate the right amount of space even before the content loads.

Load fonts properly

Fonts that swap or flash as they load can trigger layout changes. Use font-display: swap or preload fonts to maintain layout consistency.

Avoid injecting dynamic content above existing content

If your page adds banners, forms, or notifications dynamically, place them below or in a reserved space so they don’t push down existing content.

Use stable containers for third-party embeds

If you’re using embedded forms, maps, or videos from third parties, make sure they load within fixed containers to avoid unexpected shifts.

Choose a quality website builder

Using an AI website builder like B12 helps ensure your site meets web standards and avoids common layout shift pitfalls—without requiring coding knowledge.

FAQs about layout shift in web design

What is a good layout shift score?

A Cumulative Layout Shift (CLS) score under 0.1 is considered good by Google's standards. The lower, the better for user experience.

Can layout shift affect my site’s SEO?

Yes, it can. Since CLS is part of Google’s Core Web Vitals, a poor layout shift score can lower your search engine rankings.

Does layout shift happen more on mobile?

Typically, yes. Mobile screens are smaller, so shifts are more noticeable. Plus, slower mobile connections can delay how content loads, increasing the chance of shifts.

Is layout shift the same as responsive design?

No. Responsive design adjusts layout based on screen size and device. Layout shift is unexpected movement after the content starts to render, which is usually unintentional.

Do animations cause layout shift?

Not always. Well-controlled animations can enhance UX. However, if animations change element size or position unexpectedly, they might contribute to layout shifts.

Let’s aim for a stable, seamless web experience

Preventing layout shifts is less about perfection and more about improving how users experience your site. A reliable layout builds trust and keeps visitors focused on the content—not distracted by shifting buttons or bouncing images. Whether you're tweaking your code manually or using a smarter website builder, a stable layout gives your audience a smoother ride from start to finish. And if you're just starting out, you can get started with a platform like B12 to take care of the technical details for you.