Format Comparison at a Glance
| Format | Compression | Transparency | Best For |
|---|---|---|---|
| JPG | Lossy | No | Photos, maximum compatibility |
| PNG | Lossless | Yes | Logos, screenshots, graphics with text |
| WebP | Both | Yes | All web images — better JPG/PNG replacement |
| AVIF | Both | Yes | Maximum compression for web images |
| GIF | Lossless (256 colors) | Yes (1-bit) | Short animations (legacy use) |
| SVG | Vector (XML) | Yes | Logos, icons, illustrations |
| HEIC | Lossy | No | iPhone photos (Apple native) |
JPG (JPEG)
JPEG was developed in 1992 and remains the most widely supported image format. Its lossy compression algorithm works by discarding fine detail in areas where the human eye is less sensitive, making it excellent for photographs where slight quality reduction is imperceptible.
When to use JPG: Photographs destined for systems with maximum compatibility requirements — some older CMS platforms, email clients, print workflows, and legacy image processing pipelines that don't yet support WebP or AVIF. For new web projects, WebP is a better choice in virtually every scenario.
When NOT to use JPG: Logos, icons, screenshots, graphics with text, or any image requiring a transparent background. JPG doesn't support transparency (it fills transparent areas with white), and its lossy compression creates visible artifacts around sharp edges and text.
PNG
PNG (Portable Network Graphics) uses lossless compression — every pixel is preserved exactly. It supports an 8-bit alpha channel, meaning each pixel can have a different level of transparency from fully transparent to fully opaque. This makes PNG the only mainstream raster format suitable for logos and images that need to be placed on different colored backgrounds.
When to use PNG: Logos, icons, screenshots, UI mockups, images with text, and any image that needs a transparent background. Also appropriate when you need to preserve exact pixel values (for color-accurate proofing or lossless archiving).
When NOT to use PNG: Photographs. A PNG photo will be 5–20× larger than an equivalent quality JPG or WebP — there's no visual benefit for photographic content.
WebP
Google developed WebP in 2010 specifically to replace both JPG and PNG for web use. It supports both lossy and lossless compression, full alpha channel transparency, and animation. At equivalent quality, WebP lossy is 25–34% smaller than JPG, and WebP lossless is 26% smaller than PNG.
Browser support is now universal (Chrome, Firefox, Safari, Edge all supported as of 2022). The only reason to still choose JPG or PNG over WebP for new web content in 2026 is compatibility with specific tools or platforms that don't yet accept WebP uploads.
When to use WebP: All new web images — photos, graphics, blog images, product images. It's the right default format for web publishing in 2026.
AVIF
AVIF (AV1 Image File Format) is the newest major image format, derived from the AV1 video codec. It achieves even better compression than WebP — typically 50% smaller than JPG at equivalent quality. It supports HDR color, wide color gamut, and 12-bit color depth — capabilities that matter for high-end photography and professional display.
Browser support reached broad coverage by 2024 (Chrome, Firefox, Safari 16+). Encoding speed is slower than WebP, but for static images this typically only affects generation time, not display performance.
When to use AVIF: Maximum compression for images where load speed is critical, or for high-quality photography that benefits from AVIF's superior color handling.
When to Convert Image Formats
- HEIC to JPG/PNG: iPhone photos save in HEIC by default. Most websites, design tools, and sharing platforms don't accept HEIC — convert to JPG or WebP before uploading.
- PNG to WebP: If you have PNG photos (incorrectly formatted), convert to WebP for massive file size reduction. If you have PNG logos, convert to WebP lossless to maintain transparency while reducing size.
- JPG to WebP: For existing JPG image libraries, converting to WebP can reduce total storage and transfer by 25–35%.
- GIF to WebP: WebP supports animation and produces dramatically smaller animated files than GIF. Converting GIFs to animated WebP is the fastest way to reduce animated content file sizes.
- BMP/TIFF to JPG/WebP: BMP and TIFF are uncompressed formats used in some software workflows. Convert to compressed formats before web use.
Best Free Online Format Converters
Squoosh (squoosh.app): The best tool for understanding format trade-offs. You can switch between output formats and see quality and file size in real time with a split-screen preview. Handles JPG, PNG, WebP, AVIF, and more. Processes locally — nothing uploaded to a server.
CloudConvert: Supports conversion between 200+ file formats including all major image formats. The free tier allows 25 conversions per day. Batch conversion available. Useful when you need format conversion as part of a larger workflow (convert + compress + resize in one step).
iLoveIMG: Simple batch image format converter. Supports JPG, PNG, GIF, WebP, TIFF, and BMP. Free tier handles up to 30 files per task. Good for one-off batch conversions without needing an account.
FFmpeg (command-line): For bulk conversion of large image libraries, FFmpeg handles batch format conversion efficiently: ffmpeg -i input.jpg output.webp converts a single file; a shell loop handles directories. Not browser-based, but the most powerful option for technical users.
For a complete web image workflow, combine format conversion with resizing and compression. See the guides on how to resize images online and how to compress images online for the full pipeline.