Short answer: use WebP for almost everything, AVIF if you want the smallest files and can supply a fallback, SVG for logos and icons, and keep JPEG or PNG only as a backup. The longer version, and why each one exists, is below.
Images are an essential part of any website. They can help to catch attention, create a visual impact, and even establish a visual identity. It is important not only to have quality images but also to understand how different image file formats affect website performance. This blog post will provide an overview of the different image file formats and explain how to choose the best one for your website.
The Different Image File Formats
There are six formats worth knowing about on the modern web: the four long-standing ones, JPEG, GIF, PNG and SVG, plus the two newer formats that have largely replaced them for photographs, WebP and AVIF. Each has its own advantages and disadvantages. Let’s take a look at each in more detail.
JPEG
A JPEG (or Joint Photographic Experts Group) is the most common type of image file format used on websites. It provides high-quality images at relatively small sizes, making it ideal for large images that need to be compressed without sacrificing too much quality. JPEGs are also great for photos because they support millions of colours and offer options for reducing noise in pictures with low light or high contrast.
GIF
A GIF (or Graphics Interchange Format) is primarily used for animated images as it supports multiple frames per second as well as transparency. Compared to other image file formats, GIFs provide small file sizes with low-colour depth which makes them great for simple graphics like logos or icons but less suitable for photos or complex artwork due to their limited colour palette.
PNG
A PNG (or Portable Network Graphic) is similar to a JPEG in terms of quality but offers better compression rates and supports greater colour depth which makes it ideal for large images with lots of detail such as complex artwork or screenshots with text overlayed on it. However, PNGs tend to be larger than other types of files so they should not be used if size is an issue.
SVG
An SVG (or Scalable Vector Graphic) is a vector-based image format that can be scaled up or down without losing any quality since it stores data about shapes instead of pixels like other image formats do. This makes them great for logos or illustrations that need to be displayed at various sizes depending on where they’re being viewed from such as mobile devices or desktop screens with different resolutions. However, SVGs can’t store photographic data so we are not suitable for photographs or complex artworks with many colours and gradients.
WebP
WebP is Google’s replacement for JPEG and PNG, and for most websites it is now the sensible default. It handles photographs and graphics, supports transparency like a PNG and animation like a GIF, and typically produces noticeably smaller files than a JPEG at visually similar quality. Smaller files mean faster pages, which matters both for the people using your site and for how Google assesses it.
Support is no longer a concern: every current major browser reads WebP, including Safari. The main things to watch are that converting an already-compressed JPEG will not recover quality lost the first time, and that very heavy compression produces the same soft, smeared look as an over-compressed JPEG. Convert from your best original where you can.
Use it for: product photography, blog images, hero images, banners, and anything that would previously have been a JPEG or PNG.
AVIF
AVIF is the newest of the formats here and the most efficient. Built on the AV1 video codec, it generally produces smaller files than WebP at comparable quality, and it handles gradients, dark scenes and wide colour better, which is where JPEG tends to show banding. If page weight is your main problem, AVIF is the biggest single win available.
The trade-offs are practical rather than technical. Encoding is slower than WebP, older browser versions and some older devices will not display it, and not every content management system or plugin generates it automatically yet. The usual answer is to serve AVIF first with a WebP or JPEG fallback, which the <picture> element handles cleanly, so modern browsers get the smaller file and everything else still gets an image.
Use it for: large hero images, photography-heavy pages, and any site where loading speed is the priority and you can supply a fallback.
Which Format Should You Use?
- Photographs and most website images: WebP, with AVIF ahead of it if you can serve a fallback.
- Logos, icons and illustrations: SVG, because it stays sharp at any size and usually weighs very little.
- Images needing transparency: WebP first, PNG as the fallback.
- Animation: WebP or a short video file rather than a GIF, which is almost always the heaviest option.
- Screenshots with fine text: PNG or WebP in a lossless setting, so the text stays crisp.
Format is only half of it. An 8,000-pixel-wide photograph is a slow image whatever you save it as, so size images to the space they actually occupy and let the format do the rest. Our guides to website image optimisation and choosing the right image dimensions cover that side, and our guide to making the most of next-gen image file formats goes further into serving WebP and AVIF properly. If you are still sourcing the pictures, finding quality stock images is a useful starting point.
Conclusion: Understanding the differences between these image file formats will help you make informed decisions about which type best suits your needs when adding images to your website. If you want high-quality images that can easily scale up or down without losing any detail then SVG might be the best choice; if you need smaller file sizes with good colour depth then JPEG may be preferable; if you need animations then GIF could be right; and if you need both detailed imagery and small sizes then PNG could work well too! Ultimately, understanding all four file formats will help ensure that you select the right one based on your needs so that your website looks professional, loads quickly, and performs optimally!
