The Complete Image Format Guide for 2026: JPG vs PNG vs WebP vs AVIF — Krunkit Blog

Choosing the right image format can cut your page weight by 50% or more — without any visible quality loss. Yet most developers default to JPG or PNG without considering the alternatives.

This guide breaks down the four image formats that matter in 2026: JPG, PNG, WebP, and AVIF. You'll learn when to use each, how they compare on compression, and what the practical tradeoffs are.

Format Overview

| Feature | JPG | PNG | WebP | AVIF | |---------|-----|-----|------|------| | Compression | Lossy | Lossless | Both | Both | | Transparency | No | Yes | Yes | Yes | | Animation | No | APNG (limited) | Yes | Yes | | Max Colors | 16.7M | 16.7M+ | 16.7M | 16.7M+ | | HDR Support | No | No | No | Yes | | Browser Support | Universal | Universal | 97%+ | 93%+ | | Best For | Photos | Graphics/UI | General web | Maximum compression |

JPG (JPEG)

JPEG has been the default photo format since 1992. It's universally supported, well-understood, and remains the most widely used image format on the web.

How JPG Compression Works

JPEG uses a lossy compression algorithm based on the Discrete Cosine Transform (DCT). It divides the image into 8x8 pixel blocks, transforms each block into frequency components, and quantizes (rounds) the high-frequency components. This discards fine details that the human eye is less sensitive to.

The quality setting (typically 1-100) controls how aggressively the quantization step rounds values. At quality 80, most photos look indistinguishable from the original. At quality 60, compression artifacts become noticeable in gradients and fine textures.

When to Use JPG

Photographs with complex color gradients and natural scenes
Legacy compatibility when you need every device and browser to display the image
Email attachments where recipients may use older software
Print workflows that expect JPEG input

When Not to Use JPG

Images with text or sharp edges — JPEG compression blurs them
Images requiring transparency — JPEG doesn't support alpha channels
Screenshots of UI elements — PNG or WebP will be smaller and sharper
When maximum compression matters — WebP and AVIF outperform JPEG consistently

Optimization Tips

Using an optimized encoder like MozJPEG can reduce file sizes by 10-15% compared to the standard JPEG encoder at the same quality level. MozJPEG applies trellis quantization and optimized Huffman coding without any additional quality loss.

PNG

PNG (Portable Network Graphics) was created in 1996 as a patent-free alternative to GIF. It uses lossless compression, meaning every pixel is preserved exactly.

How PNG Compression Works

PNG uses the DEFLATE algorithm (the same used by ZIP files) applied to filtered pixel data. Before compression, PNG applies filters to each row of pixels that predict pixel values based on neighboring pixels. The better the prediction, the more compressible the data becomes.

PNG-8 supports up to 256 colors with a palette, while PNG-24/32 supports full 24-bit color plus an 8-bit alpha channel for transparency.

When to Use PNG

Screenshots and UI captures — PNG preserves sharp text and edges perfectly
Logos and icons with flat colors and sharp boundaries
Images requiring transparency — PNG's alpha channel supports 256 levels of transparency
Graphics with text — rendered text stays crisp and legible
Source files when you need lossless quality for future editing

When Not to Use PNG

Photographs — PNG files of photos are 5-10x larger than equivalent JPEGs with no visible benefit
Large images where file size matters — consider WebP lossless instead (20-30% smaller)
Animated content — while APNG exists, WebP and AVIF animations are more efficient

Optimization Tips

Tools like OxiPNG can reduce PNG file sizes by 10-30% by trying multiple filter and compression strategies. This is fully lossless — the output is pixel-identical to the input, just stored more efficiently.

WebP

WebP was developed by Google and released in 2010. It supports both lossy and lossless compression, transparency, and animation in a single format.

How WebP Compression Works

WebP lossy compression is based on VP8 video codec technology. It uses block prediction, where each block of pixels is predicted from already-decoded blocks, and only the difference (residual) is encoded. This approach is fundamentally more efficient than JPEG's DCT-based method for most images.

WebP lossless compression uses a combination of transforms: spatial prediction, color space transform, subtract green transform, and LZ77-Huffman coding. The result is typically 20-30% smaller than PNG.

Compression Comparison

| Image Type | JPG (q80) | PNG | WebP Lossy (q80) | WebP Lossless | |------------|-----------|-----|-------------------|---------------| | Photo (2MP) | 320 KB | 4.2 MB | 210 KB | 2.8 MB | | Screenshot | 180 KB | 95 KB | 85 KB | 68 KB | | Logo (simple) | 25 KB | 12 KB | 14 KB | 9 KB | | Illustration | 150 KB | 280 KB | 95 KB | 195 KB |

Sizes are approximate and vary by image content.

When to Use WebP

General web images — WebP is the best all-around format for web use
When you need one format that does everything — lossy, lossless, transparency, animation
E-commerce product photos — smaller files mean faster page loads and better conversion rates
Social media assets — most platforms now accept WebP

When Not to Use WebP

Print workflows — most print software doesn't accept WebP
When AVIF is an option — AVIF achieves 20-30% better compression in most cases
Legacy systems — some older image editors and CMS platforms may not support WebP

Browser Support

WebP is supported by all modern browsers including Chrome, Firefox, Safari, Edge, and Opera. Safari added WebP support in version 14 (2020), making it effectively universal. As of 2026, global browser support exceeds 97%.

AVIF

AVIF (AV1 Image File Format) is the newest format in this comparison, based on the AV1 video codec developed by the Alliance for Open Media. It offers the best compression ratios of any current image format.

How AVIF Compression Works

AVIF leverages the AV1 intra-frame encoding, which uses larger and more flexible block sizes (up to 64x64 pixels), directional intra prediction with dozens of modes, and advanced in-loop filtering. These techniques allow AVIF to maintain quality at dramatically lower file sizes.

AVIF also supports features no other web format offers:

HDR (High Dynamic Range) — wider brightness range than standard displays
Wide color gamut — P3 and Rec. 2020 color spaces
12-bit depth — 4,096 levels per channel vs. 256 for 8-bit formats
Film grain synthesis — adds natural grain at decode time, saving bits

Compression Comparison vs. WebP

| Quality Level | WebP | AVIF | AVIF Savings | |--------------|------|------|-------------| | High (q80) | 210 KB | 145 KB | 31% | | Medium (q60) | 125 KB | 82 KB | 34% | | Low (q40) | 78 KB | 48 KB | 38% |

Based on a typical 2MP photograph. Results vary by image content.

AVIF achieves 20-40% smaller files than WebP at equivalent visual quality, with the greatest savings at lower quality settings.

When to Use AVIF

Maximum compression — when every kilobyte counts
Hero images and above-the-fold content — AVIF's superior compression means faster LCP (Largest Contentful Paint)
Photography portfolios — AVIF preserves fine detail at lower file sizes than any alternative
HDR content — AVIF is the only web format with full HDR support

When Not to Use AVIF

Encoding speed matters — AVIF encoding is 5-10x slower than WebP. For real-time applications, WebP may be more practical
Tiny images — for images under 10 KB, the overhead of AVIF's container can negate the compression advantage
Very old browsers — IE and some legacy mobile browsers don't support AVIF

Browser Support

AVIF support has grown rapidly. Chrome, Firefox, Samsung Internet, and Opera have supported AVIF since 2021. Safari added support in version 16 (2022). As of 2026, global browser support exceeds 93%.

Practical Recommendations

For Web Developers

Use the <picture> element to serve the best format each browser supports:

<picture>
  <source srcset="image.avif" type="image/avif" />
  <source srcset="image.webp" type="image/webp" />
  <img src="image.jpg" alt="Description" />
</picture>

This approach serves AVIF to browsers that support it (best compression), falls back to WebP (good compression), and uses JPG as the universal fallback.

For Social Media

Most social media platforms now accept WebP. However, some platforms re-encode uploads, so starting with the highest quality source is more important than the format choice. Use PNG for graphics with text, and high-quality JPG or WebP for photos.

For Email

Stick with JPG and PNG for email. Email client support for WebP and AVIF is inconsistent, and many corporate email systems strip or block newer formats.

Decision Flowchart

Need transparency? → WebP (lossy or lossless) or AVIF
Need lossless quality? → WebP lossless (smallest) or PNG (most compatible)
Photo for the web? → AVIF first, WebP fallback, JPG as universal fallback
Screenshot or UI element? → WebP lossless or PNG
Need universal compatibility? → JPG for photos, PNG for graphics
Print or email? → JPG or PNG

File Size Impact on Web Performance

Image optimization directly impacts Core Web Vitals, which Google uses as a ranking signal.

| Metric | What It Measures | Image Impact | |--------|-----------------|-------------| | LCP | Largest Contentful Paint | Hero images are often the LCP element | | CLS | Cumulative Layout Shift | Proper width/height prevents layout shift | | INP | Interaction to Next Paint | Large images can block the main thread |

Switching from unoptimized JPG to optimized AVIF typically reduces image payload by 60-80%. On a page with 1 MB of images, that's 600-800 KB saved — a significant improvement in load time, especially on mobile networks.

Convert Between Formats

Need to convert between formats? Krunkit's converter tool supports JPG, PNG, WebP, and AVIF — all processed in your browser using WASM. No uploads, no quality loss from server re-encoding, and you keep full control of your files.