What Is The Best Image Format For Web? Which One To Choose?

, Web

What Is The Best Image Format For Web? Which One To Choose?

An average mobile webpage is 2.2MB and 68% of it is images. So, image has huge importance on web page speed. Image formats are very important as well. First, let's see what kinds of image formats are widely used on web.

JPG/ JPEG (Joint Photographic Experts Group)

JPEG is perhaps the most common image format used on the web. Its standard was created in 1992 (latest version, 1994) as the result of a process which started in 1986. Although this standard is generally considered as a single specification, in reality it is composed of four separate parts and an amalgam of coding modes.*

JPEG is a lossy format, so there is always some loss of quality when using this format. On the other hand, it is the most compatible format for web. Nearly all of the browsers are supporting JPEG format.

GIF (Graphics Interchange Format)

GIF is a bitmapimage format developed by a team at the online services provider CompuServe led by American computer scientist Steve Wilhite on June 15, 1987.  

GIFs are suitable for sharp-edged line art (such as logos) with a limited number of colors and can be used for animations and low-resolution videos.

PNG (Portable Network Graphics)

PNG is mostly known for its transparency feature. Besides RGB (Red-Green-Blue) channels PNG also has alpha channel for transparency. Additionally, PNG supports lossless compression.

PNG supports palette-based images, grayscale images (with or without alpha channel for transparency), and full-color non-palette-based RGB/RGBA images (with or without alpha channel).


WebP is a method of both lossy and lossless compression that can be used on a large variety of photographic, translucent and graphical images found on the web. The degree of lossy compression is adjustable, so the user can choose the degree of trade-off between file size and image quality.

WebP is an image format developed by Google. This format was designed to be used specifically on the web. Even though WebP has a huge advantage for size of image, some of the browsers don't support WebP.

Which one to choose?

When it comes to choose the best option for your websites, there are two important points to consider: Size and Compatibility.

Size varies across the images. Pictures may have smaller size with WebP and logo/graphics may have smaller size with PNG.

JPEG, GIF and PNG are supported by many common browsers. Even though WebP has its size advantages, it is not supported by some browsers.

image4io Auto Format Delivery

image4io has the ability to automatically detect which browser is requesting the image and then select the most efficient image format to be delivered. image4io auto format delivery considers both compatibility and size to deliver the best option for your customers.

With this feature, image4io users doesn't have to decide which image format to use on development time. Web developers can work without thinking about their source image formats and which format to deliver to their customers. image4io decides and delivers best option from any source format via multi-CDN architecture.

use image4io to optimize your websites' images.