The Format Choice That Affects Every Image on the Web
Every image on the web is stored in a format. That format determines how much space the image takes up, whether it can have a transparent background, how well it compresses, and how widely it is supported across browsers and devices.
Choosing the wrong format does not break anything — but it costs performance. A PNG used where a JPG would do uses 5–10× more bandwidth. A JPG used where a PNG should be loses detail and introduces visible artifacts. A site still serving old GIFs for animations when WebP or AVIF is supported wastes significant bandwidth.
Here is the decision framework that most professional web developers use.
JPG (JPEG): For Photographs
JPG uses lossy compression. When you save an image as a JPG, the algorithm analyzes the image and discards some data — specifically, small variations in color that the human eye is less sensitive to. The result is a much smaller file. The trade-off is that quality degrades slightly with each save, and at low quality settings, you can see the compression artifacts: blurring, blocky regions (called "mosquito noise"), and color banding.
Use JPG when:
- The image is a photograph with complex gradients and many colors
- You want the smallest possible file size and can accept slight quality loss
- The image does not need a transparent background
- You will not be editing and re-saving the image many times (each save degrades quality)
Avoid JPG when:
- The image has text, sharp lines, or flat areas of color (logos, screenshots)
- You need a transparent background
- You need to preserve exact pixel values (for professional editing workflows)
Typical JPG file size for a high-resolution photo: 2–5 MB. At web-optimized quality (80–85% quality setting): 200–600 KB.
PNG: For Graphics and Transparency
PNG uses lossless compression. No data is discarded. The image you get out is pixel-for-pixel identical to the image you put in. PNG also supports transparency (an alpha channel), which JPG does not.
Use PNG when:
- The image has text, logos, icons, or sharp edges that would show JPG artifacts
- You need transparency (a transparent background so the image can overlay other content)
- You are creating screenshots or screen recordings (sharp UI elements)
- You need to preserve exact color values for editing
Avoid PNG when:
- The image is a photograph — PNG makes photos 5–10× larger than JPG with no perceptible quality benefit
- You are optimizing for page load speed and the image does not require transparency or sharp edges
Typical PNG file size for a high-resolution photo: 5–20 MB. For a logo with transparency: 10–200 KB depending on complexity.
WebP: The Modern Default
WebP was developed by Google and released in 2010. It supports both lossy and lossless compression, and also supports transparency. In both modes, it achieves smaller file sizes than JPG and PNG while matching or exceeding their quality.
WebP lossy images are typically 25–35% smaller than equivalent JPG images at the same quality level. WebP lossless images are typically 26% smaller than equivalent PNG files.
Browser support: WebP is now supported in all modern browsers — Chrome, Firefox, Safari (since 14, 2020), Edge, and Opera. If you are building for the modern web, WebP is the best default choice for both photographs and graphics.
Use WebP when:
- You want the smallest file size for the best quality
- You are serving images on the web
- Your audience uses modern browsers (which is almost everyone now)
GIF: For Simple Animations Only
GIF is an old format (1987) that supports simple animations. It is limited to 256 colors per frame, which makes it poor for photographs. For simple pixel art, small icons, and very short animations, it remains in use.
Modern replacement: WebP supports animation. A WebP animation is typically 64% smaller than an equivalent GIF. If you can use WebP, use WebP instead of GIF.
AVIF: The Future Format
AVIF (AV1 Image File Format) is newer than WebP and achieves even better compression — often 50% smaller than equivalent JPG at the same quality. Browser support is growing but not yet universal (Chrome and Firefox support it; Safari support arrived in version 16).
For cutting-edge performance optimization, AVIF is worth testing. For broad compatibility today, WebP is the safer choice.
How to Use the Toobits Image Converter
Upload your image, select the output format, and download the converted file. Conversion happens entirely in your browser — no upload to any server, no privacy concern. Useful for converting old PNG photographs to WebP for web performance, converting JPG screenshots to PNG to preserve sharpness, or converting GIFs to WebP to reduce animation file size.