The 3 Best Image Formats for Website Performance

Choosing the right image format is crucial for your website’s performance and user experience. Twenty years ago, formats like GIF and JPG dominated due to their simplicity and compatibility. However, with advancements in web technology, newer formats have emerged. In this article, we will explore the categories, formats, and gold standards of image formatting as concisely as possible (we don’t like reading long articles either!).

Categories of Image Formats:

  1. Bitmap (Raster) Graphics: Images made up of a grid of pixels.
  2. Vector Graphics: Images created using mathematical equations and geometric shapes.

Common Formats:

  • Bitmap (Raster) Formats: JPG, PNG, GIF, BMP, WebP, TIFF
  • Vector Formats: SVG, PDF, EPS, AI

The Gold Standard:

Let’s cut to the chase and explain the best three image formats to use in 2024.

1. WebP

  • Stands for: Web Picture Format
  • Type: Bitmap
  • Pros: High compression efficiency, supports both lossy and lossless compression, includes transparency (alpha channel), and supports animations.
  • Cons: Not universally supported by all browsers and image editors, though support is widespread.
  • Where to use it: Ideal for general web images, product photos on e-commerce sites, and animated graphics. For example, use WebP for optimising images on a blog or for dynamic content on a retail website.

2. SVG

  • Stands for: Scalable Vector Graphics
  • Type: Vector
  • Pros: Scalable without loss of quality, small file size, ideal for logos, icons, and illustrations, supports interactivity and animation.
  • Cons: Not suitable for detailed images like photographs, complex images can become large and slow to render.
  • Where to use it: Best for logos, icons, infographics, and interactive web elements. For example, use SVG for a website’s logo or interactive maps and diagrams.

3. PNG

  • Stands for: Portable Network Graphics
  • Type: Bitmap
  • Pros: Lossless compression, supports transparency (alpha channel), good for detailed images and images requiring sharp edges and text.
  • Cons: Larger file sizes compared to lossy formats like JPG, not suitable for very large images due to file size.
  • Where to use it: Perfect for images needing transparency, detailed graphics, and images with text. For example, use PNG for website headers, detailed icons, and images with text overlays.

The Other Common Formats

These formats have specific use cases but are not the gold standard for web development in 2024.

4. JPG (JPEG)

  • Stands for: Joint Photographic Experts Group
  • Type: Bitmap
  • Pros: Excellent for photographs due to lossy compression, small file size, widely supported.
  • Cons: Lossy compression can reduce image quality, does not support transparency.

5. GIF

  • Stands for: Graphics Interchange Format
  • Type: Bitmap
  • Pros: Supports simple animations, widely supported, good for simple graphics with limited colors.
  • Cons: Limited to 256 colors, not suitable for detailed images, larger file sizes for high-quality images.

6. BMP

  • Stands for: Bitmap
  • Type: Bitmap
  • Pros: Simple and widely supported, uncompressed format ensures no loss of quality.
  • Cons: Very large file sizes, not suitable for web due to slow loading times.

7. TIFF

  • Stands for: Tagged Image File Format
  • Type: Bitmap
  • Pros: Lossless compression, excellent for high-quality prints and professional photography.
  • Cons: Large file sizes, not supported by all browsers, slow loading times.

8. PDF

  • Stands for: Portable Document Format
  • Type: Vector (can include bitmaps)
  • Pros: Ideal for documents, maintains formatting across different devices, supports interactivity.
  • Cons: Not primarily an image format, larger files for image-heavy documents, requires a viewer plugin or software.

9. EPS

  • Stands for: Encapsulated PostScript
  • Type: Vector
  • Pros: Excellent for high-quality prints and scalable graphics, supports transparency.
  • Cons: Larger file sizes, not suitable for web use due to limited browser support.

10. AI

  • Stands for: Adobe Illustrator
  • Type: Vector
  • Pros: Ideal for creating and editing vector graphics, widely used in professional design.
  • Cons: Proprietary format, not suitable for web use without conversion, requires Adobe Illustrator to edit.

What Size Should They Be?

The ideal image size depends on the application, but there are general guidelines to follow for optimal web performance:

  • WebP: For general use, aim for images around 1920 pixels wide for full-width images. For smaller elements like thumbnails, 300-600 pixels wide is typically sufficient.
  • SVG: Since SVGs are vector-based and scalable, they don’t have a set resolution. However, ensure the aspect ratio fits your design and avoid overly complex SVGs to keep file sizes manageable.
  • PNG: For detailed images or those requiring transparency, use around 1920 pixels wide for full-screen images. For smaller graphics like icons, 100-500 pixels wide works well.

A good website will automatically resize, scale, and optimise images based on the device and display size. Therefore, using a larger format around 1920 pixels wide ensures that the images are clear on high-resolution screens. Always check with your web developer for specific recommendations and implementation details to ensure optimal performance and quality.

General Guidelines

  • Full-width images: 1920 pixels wide
  • Medium images: 800-1200 pixels wide
  • Thumbnails/icons: 100-600 pixels wide

These guidelines help maintain a balance between image quality and loading speed. Your website should handle resizing and optimisation, so starting with a large, high-quality image ensures the best results across all devices.

Conclusion

While WebP, SVG, and PNG stand out as the top choices for web development in 2024 due to their balance of quality, file size, and compatibility, other formats like JPG, GIF, BMP, TIFF, PDF, EPS, and AI have specific use cases that make them valuable in particular scenarios. Understanding the strengths and limitations of each format helps in selecting the right one for any given task.

Author Photo

By Eliot Webb