You take a photo on your iPhone and it saves as HEIC. You download an image from the web and it is WebP. You export from Photoshop and you are choosing between JPEG and PNG. Your developer colleague mentions AVIF. With so many image formats in use today, it is easy to feel confused about which one to pick and why.
This article breaks down the most common image formats, explains the technology behind each, and gives you clear guidance on when to use what.
Lossy vs Lossless: The Fundamental Divide
Every image format falls into one of two categories:
- Lossy compression permanently discards some image data to achieve smaller files. You cannot get the original quality back. The trade-off is much smaller file sizes.
- Lossless compression reduces file size without losing any image data. The decompressed image is pixel-for-pixel identical to the original.
Some formats support both modes. Understanding this distinction is key to choosing the right format.
The Formats Explained
JPEG (JPG)
Created in 1992, JPEG is the most widely used image format in the world. It uses lossy compression based on how the human eye perceives color, discarding details that are less noticeable.
- Best for: Photographs, complex images with many colors and gradients
- Not ideal for: Text, line art, logos, images requiring transparency
- Transparency: Not supported
- Animation: Not supported
- Quality control: Adjustable compression level (typically 60-95%)
JPEG excels at photographs because the subtle detail loss is nearly invisible, while the file size reduction can be dramatic — often 10x smaller than an uncompressed image.
PNG
Introduced in 1996 as a patent-free alternative to GIF, PNG uses lossless compression. Every pixel is preserved exactly.
- Best for: Screenshots, logos, icons, text overlays, images needing transparency
- Not ideal for: Large photographs (files become very large)
- Transparency: Full alpha channel (256 levels of transparency)
- Animation: Supported via APNG (limited browser support historically, now widely supported)
PNG is the go-to format when you need crisp edges, text readability, or transparent backgrounds.
WebP
Developed by Google and released in 2010, WebP was designed to be a universal replacement for both JPEG and PNG. It supports lossy and lossless compression, transparency, and animation — all in one format.
- Best for: Web images of all kinds, replacing both JPEG and PNG
- Not ideal for: Print workflows, environments where universal compatibility is critical
- Transparency: Yes (both lossy and lossless modes)
- Animation: Yes (replacing animated GIFs with much smaller files)
- Size advantage: Typically 25-35% smaller than equivalent JPEG, 25% smaller than PNG
As of 2026, WebP is supported by all major browsers and has become the default image format for many websites.
HEIC / HEIF
HEIC (High Efficiency Image Container) is the format Apple adopted for iPhone photos starting with iOS 11 in 2017. It is based on the HEVC (H.265) video codec.
- Best for: Mobile photography, Apple ecosystem
- Not ideal for: Web publishing, cross-platform sharing
- Transparency: Yes
- Animation: Yes (image sequences)
- Size advantage: Roughly 50% smaller than JPEG at comparable quality
HEIC produces excellent quality at small file sizes, but its main limitation is compatibility. Windows and many web platforms require conversion before use.
AVIF
The newest contender, AVIF (AV1 Image File Format), is based on the open-source AV1 video codec. It is backed by major tech companies including Google, Netflix, and Mozilla.
- Best for: Web images where maximum compression is desired
- Not ideal for: Workflows requiring fast encoding (AVIF is slow to encode)
- Transparency: Yes
- Animation: Yes
- Size advantage: Typically 20-30% smaller than WebP, 50%+ smaller than JPEG
AVIF offers the best compression ratios available today, but encoding is slower and tool support is still maturing.
Format Comparison Table
| Feature | JPEG | PNG | WebP | HEIC | AVIF |
|---|---|---|---|---|---|
| Compression | Lossy | Lossless | Both | Both | Both |
| Transparency | No | Yes | Yes | Yes | Yes |
| Animation | No | APNG | Yes | Yes | Yes |
| File size (photo) | Medium | Large | Small | Small | Smallest |
| Browser support | Universal | Universal | Universal | Limited | Wide |
| Encoding speed | Fast | Fast | Fast | Fast | Slow |
| Best use case | Photos | Graphics | Web (all) | Mobile | Web (next-gen) |
Practical Decision Guide
Use this simple flowchart to pick the right format:
- Is it a photograph for the web? Use WebP (or AVIF if your platform supports it). Fall back to JPEG for maximum compatibility.
- Does it need transparency? Use WebP or PNG. Choose PNG if you need guaranteed universal compatibility.
- Is it a logo, icon, or screenshot? Use PNG for lossless quality, or WebP lossless for smaller files.
- Is it an animation? Use WebP instead of GIF — dramatically smaller files with better quality.
- Is it for Apple devices only? HEIC is fine. Otherwise, convert to JPEG or WebP before sharing.
- Is it for print? Use TIFF or PNG for lossless quality. JPEG at maximum quality is also acceptable.
Tip. When you receive a HEIC file from an iPhone and need to share it more widely, converting it to JPEG or WebP is usually the best approach. The quality loss from a single conversion is negligible, but the compatibility gain is significant.
The Future of Image Formats
The trend is clear: newer formats achieve better compression with higher quality. AVIF is poised to become the dominant web format over the next few years, but WebP has already achieved critical mass and will remain widely used. JPEG and PNG are not going away — their universal support and simplicity ensure they will coexist alongside newer formats for a long time.
Going Further
ToolK.io provides free tools to convert between image formats, compress images for the web, and work with HEIC files, along with step-by-step tutorials for every common image task.