TL;DR: Use WebP as your default web image format. Fall back to JPG for photographs where WebP is not supported, and PNG for images that need transparency or pixel-perfect sharpness. Consider AVIF for maximum compression if your audience uses modern browsers.
Format Comparison at a Glance
| Feature | JPG | PNG | WebP | AVIF |
|---|---|---|---|---|
| Compression | Lossy | Lossless | Lossy + lossless | Lossy + lossless |
| Transparency | No | Yes (alpha) | Yes (alpha) | Yes (alpha) |
| Animation | No | No (use APNG) | Yes | Yes |
| Typical file size | Medium | Large | Small | Smallest |
| Browser support | Universal | Universal | 97%+ globally | 93%+ globally |
| Best for | Photos, social sharing | Logos, icons, screenshots | General web use | Performance-critical sites |
JPG (JPEG)
JPG has been the default photo format on the web since the mid-1990s. It uses lossy compression, meaning it discards some image data to reduce file size. At moderate quality settings (75-85%), the visual difference from the original is usually imperceptible to most viewers.
Strengths
- Universal browser and device support, including email clients and social platforms.
- Good compression for photographs and complex images with gradients.
- Every image editor, CMS, and CDN handles JPG without configuration.
Weaknesses
- No transparency support. You cannot place a JPG on a non-white background cleanly.
- Lossy compression creates visible artifacts on text, line art, and sharp edges.
- Re-saving a JPG degrades quality each time (generation loss).
Use JPG when: you are serving photographs, have no transparency needs, and need universal compatibility (email newsletters, social media thumbnails, older systems).
PNG
PNG uses lossless compression, preserving every pixel exactly as authored. The format supports full alpha transparency, which makes it the standard for logos, icons, UI elements, and any image placed on variable backgrounds.
Strengths
- Lossless quality with no compression artifacts.
- Full alpha channel for transparency and semi-transparency.
- Sharp rendering of text, line art, and geometric shapes.
Weaknesses
- File sizes are significantly larger than JPG or WebP for photographic content.
- Not practical for large hero images or photo galleries due to size.
- No native animation (APNG exists but has limited tooling).
Use PNG when: you need transparency, are serving logos or icons, or require lossless quality for screenshots and diagrams.
WebP
WebP was developed by Google and released in 2010. It supports both lossy and lossless compression, transparency, and animation in a single format. At equivalent visual quality, WebP files are typically 25-35% smaller than JPG and significantly smaller than PNG.
Strengths
- Smaller files than both JPG and PNG at comparable quality.
- Supports transparency and animation in one format.
- Supported by Chrome, Firefox, Safari, Edge, and all major mobile browsers (97%+ global coverage).
Weaknesses
- Some older email clients and legacy systems do not support WebP.
- Social media platforms sometimes re-encode WebP uploads to JPG.
- Slightly slower to encode than JPG at high compression ratios.
Use WebP when: you control the delivery environment (your own website), want the best balance of quality and file size, and can provide a JPG fallback for edge cases.
AVIF
AVIF is based on the AV1 video codec and delivers the best compression ratios of any current image format. A typical AVIF file is 20% smaller than WebP and up to 50% smaller than JPG at similar visual quality. Browser support has grown rapidly since 2022.
Strengths
- Best-in-class compression: noticeably smaller files than WebP.
- Supports transparency, HDR, wide color gamut, and animation.
- Supported in Chrome, Firefox, Safari 16.4+, and Edge (93%+ globally).
Weaknesses
- Encoding is slow compared to JPG or WebP, making on-the-fly generation expensive.
- Not yet supported in all image editors and CMS platforms.
- Some older Safari and iOS versions lack support.
Use AVIF when: you can pre-generate images (build step or CDN), your audience uses modern browsers, and page speed is a top priority. Always provide a WebP or JPG fallback.
Decision Tree: Which Format Should You Use?
- Does the image need transparency? If yes, use WebP (or PNG as fallback). If AVIF support is sufficient for your audience, AVIF works too.
- Is it a photograph or complex image? Use WebP as the default. Serve AVIF for modern browsers if you can generate it. Fall back to JPG for email and social sharing.
- Is it a logo, icon, or diagram? Use SVG if possible (vector). Otherwise, use PNG for lossless quality or WebP for smaller files.
- Is page speed critical? Use AVIF with WebP fallback. Implement the HTML
<picture>element to let the browser pick the best supported format. - Do you need universal compatibility? Use JPG for photos and PNG for transparency. These work everywhere, including email clients, social platforms, and legacy systems.
Practical tip: Use the HTML <picture> element to serve AVIF to browsers that support it, WebP as a middle option, and JPG as the universal fallback. This gives every visitor the best format their browser can handle.
How to Convert Between Image Formats
If you have images in one format and need another, you can convert them without installing software. FastlyConvert handles common conversions directly in the browser:
- JPG to PNG for adding transparency to photos.
- WebP to JPG for social sharing or email compatibility.
- HEIC to JPG for converting iPhone photos to a universal format.
- Image Resizer for adjusting dimensions before upload.
Frequently Asked Questions
Should I use WebP instead of JPG on my website? expand_more
For most websites, yes. WebP produces files 25-35% smaller than JPG at similar visual quality and supports transparency. All major browsers now support WebP. The main exception is if you need to serve images to very old browsers or email clients that only accept JPG.
When should I use PNG instead of JPG? expand_more
Use PNG when you need transparency (logos, icons, overlays), sharp edges on text or line art, or lossless quality where every pixel matters. For photographs and complex images without transparency, JPG is almost always smaller and visually equivalent.
Is AVIF ready for production websites? expand_more
AVIF is supported in Chrome, Firefox, and Safari 16.4+. It offers better compression than WebP but takes longer to encode. For sites that serve many images and can generate AVIF versions in advance, it is production-ready. Use it with a WebP or JPG fallback for maximum compatibility.
What image format is best for e-commerce product photos? expand_more
WebP is the best default for e-commerce product photos because it balances small file size with high visual quality. Use PNG only for products on transparent backgrounds. Serve AVIF where supported for additional savings. Always provide a JPG fallback for email and social sharing.
How do I convert images between formats for free? expand_more
FastlyConvert offers free browser-based image conversion between JPG, PNG, WebP, HEIC, and other formats. Upload your image, select the output format, and download the result. Many conversions run directly in the browser, so your file is not uploaded to a server.