SVG vs PNG Icons for Web Development

Tuesday, January 28, 2025 • by Svg/Icons Team • 7 min read

As a web developer, you face countless decisions every day that influence how you build, optimize, and present content. One of these decisions is selecting the right image format for icons. In particular, SVG (Scalable Vector Graphics) and PNG (Portable Network Graphics) are two commonly used formats you’ll see in practice. Both have their merits, but how do you decide which one is best for your use case?

This article delves into the pros and cons of each format, covering everything from scalability to performance. By the end, you’ll have a clear understanding of when to choose SVGs over PNGs (and vice versa), and how to get the most out of either format. Let’s get started!

What Are SVGs and PNGs?

Before diving into the nuances, let’s define these image formats briefly:

  • SVGs: A vector-based image format defined by XML markup. Instead of storing pixels, SVGs store instructions on how to draw shapes, lines, and colors. This allows SVGs to be scaled up or down without losing quality.
  • PNGs: A raster or pixel-based format. PNGs store individual pixel information, making them ideal for detailed images or photos. They also support lossless compression and transparency (including alpha channels).

Why You Might Want to Use SVGs

SVGs are incredibly versatile. If you’re building a modern site or application that needs crisp, scalable icons across a variety of screen sizes and pixel densities, SVGs often come out on top. Here’s why:

  • Scalability: Because SVGs are vector-based, you can resize them infinitely without losing quality. This is essential for responsive designs and high-DPI (e.g., Retina) displays.
  • Styling with CSS: Since SVGs are essentially XML, you can use CSS to change their appearance on the fly. Want your icon to turn red on hover? No problem! This also reduces the need for multiple raster images at different color states.
  • Inline Manipulation: When you embed an SVG inline (using <svg>...</svg> in HTML), it becomes part of the DOM. You can then use JavaScript to animate, modify, or interact with the elements inside the SVG in real time. This level of control can open up a world of creativity for hover effects, transitions, or even interactive infographics.
  • Smaller File Size (for simple icons): SVGs describing basic shapes (like a plus sign or a magnifying glass) can be incredibly small. If you compress them using tools like SVGO, you can reduce your icon set size even further.

Why You Might Still Use PNGs

Despite the many advantages of SVGs, you might still encounter scenarios where PNGs make more sense. Depending on your project or audience, consider the following:

  • Complexity of the Graphic: Photos and complex artwork with gradients, textures, or large amounts of detail might be more efficient to store and render as a PNG (or other raster formats like JPEG or WebP). Converting a photo to an SVG is typically impractical.
  • Legacy Browser Support: While SVG support is excellent in modern browsers, older browsers (especially Internet Explorer 8 and below) lack native support. If you need to reach these older audiences and don’t want to rely on polyfills or fallback strategies, PNG might be the safer choice.
  • Performance Considerations at Scale: Although typical single SVG icons don’t require significant CPU power, some older mobile devices or less capable browsers may struggle if you have hundreds of inline SVGs on one page. In these scenarios, PNGs might be more performant.
  • Existing Workflows: Many design tools and pipelines are set up around PNG generation and sprite sheet creation. If your team is deeply invested in a workflow that relies on PNG sprites, you might opt to continue using that pipeline for speed and efficiency.

Performance: Is CPU Overhead a Concern?

You may have heard that SVGs are CPU-intensive to render. Technically, every time the browser zooms or redraws an SVG, it needs to recalculate the vector shapes, whereas PNG is just a fixed set of pixels. However, for simple icons and logos, the overhead is usually minimal in modern browsers. The trouble arises when:

  • You embed hundreds or thousands of inline SVGs into your DOM.
  • You create extremely complex vectors with numerous paths, shapes, and filters.

In those rare cases, you might experience noticeable lag—especially on older mobile devices. A workaround is using SVG Sprites, where you reference an SVG from a single file, rather than embedding it inline multiple times. This approach reduces DOM bloat and can significantly improve performance.

Using SVGs as Sprites

If you decide to incorporate many icons, it’s best to use an SVG sprite. The general idea is straightforward: 

<svg style="display: none;">
    <symbol id="icon-check" viewBox="0 0 24 24">
        <!-- SVG paths for check icon -->
    </symbol>

    <symbol id="icon-close" viewBox="0 0 24 24">
        <!-- SVG paths for close icon -->
    </symbol>

    <!-- More icons... -->
</svg>

<!-- Later in your HTML -->
<svg class="icon">
    <use xlink:href="#icon-check"></use>
</svg>

You only load one SVG file, and each icon is referenced via its <symbol> ID. This approach greatly reduces the number of HTTP requests. It also simplifies maintenance because you can manage all your icons in a single place.

Accessibility and Semantics

When embedding icons, whether SVG or PNG, accessibility is key. You want users who rely on screen readers to understand what the icon represents. Here’s how to ensure accessibility:

  • Use <title> Tags for SVGs: Provide a short descriptive title within the SVG code (especially if embedded inline).
  • Add aria-label or role="img": Make sure your SVGs can be interpreted correctly by assistive technologies.
  • Use alt Attributes on <img> for PNGs: Give a textual description of what the icon stands for.

Icon Fonts vs. SVG Icons

Some teams still rely on icon fonts (e.g., Font Awesome) for the simple reason that they’re easy to implement with CSS pseudo-elements (::before or ::after). However, icon fonts have their drawbacks:

  • Fonts can break if a user disables web fonts or overrides default fonts.
  • They may lack the visual crispness that comes with vector SVGs on high-density displays.
  • Accessibility can be tricky because the icons are technically text characters.

If you only need a few icons or want to ensure maximum clarity, SVG icons are generally the recommended approach in modern web development.

Best Practices for SVG Usage

Ready to go all-in on SVGs? Here are some tips to keep things efficient and maintainable:

  • Optimize Your SVGs: Use tools like SVGO or ImageOptim to strip out unnecessary comments and metadata. This can drastically reduce file sizes.
  • Use a Build Process: If you have a large icon library, consider automating sprite generation using tools like Webpack, Gulp, or Grunt. This setup can integrate well with a modern front-end pipeline.
  • Minimize Inlined SVGs: Only inline what you need to animate or style dynamically. For purely static icons, referencing them via <img> or background-image might suffice.
  • Fallbacks: If you need to support users on really old browsers, provide a PNG fallback or a polyfill. You can conditionally load these based on user agents or feature detection.

When PNG Is Still the Way to Go

While you’ll likely find yourself using SVGs for most modern websites and apps, there are times when PNG just makes more sense:

  • Legacy Clients: If you’ve got a large user base on IE8 or older, maintaining SVG support can become a challenge. That may justify sticking to PNG icons.
  • Static Images / Thumbnails: If the icon is a detailed image or photo, PNG (or WebP/JPEG) is the better choice—vectors aren’t meant for photorealistic content.
  • Team Workflow: If switching to an SVG-based workflow disrupts your entire design-to-dev pipeline, the cost of re-engineering might outweigh the benefits—at least in the short term.

Conclusion

In today’s web ecosystem, SVG is often the optimal choice for icons. You get flexible styling, effortless scalability, and the capacity for advanced interactivity. PNG, however, still plays a crucial role in handling complex images, supporting older browsers, or fitting neatly into legacy workflows.

Ultimately, there is no single correct answer—it depends on the needs of your project, your audience, and your existing toolchain. If you’re already building for modern browsers and you want to future-proof your design with high-quality vector icons, you’ll likely find that SVGs win out for most use cases. For developers targeting older devices or dealing with complex, photorealistic images, PNGs (or other raster formats) may still be your go-to.

Whichever path you choose, remember to keep an eye on performance, maintainability, and accessibility. By focusing on these principles, you’ll create a top-notch user experience that looks great on all devices and browsers—both present and future!

Key Takeaways

  • SVGs: Ideal for icons, logos, and simple graphics that need scalability and easy styling.
  • PNGs: Better for complex images or when you need to ensure compatibility with very old browsers.
  • Performance: Simple icons as SVGs are usually lightweight, but very large numbers of inline SVGs can increase rendering overhead.
  • Workflow: Use automated tools (SVGO, Webpack, Gulp, etc.) to generate and optimize SVG sprites.
  • Accessibility: Don’t forget to label your icons (title, alt, aria-label) for users with screen readers.