JPEG vs PNG vs WebP vs AVIF: The Definitive Format Guide

Every image format falls into one of two fundamental compression categories and understanding the difference will save you from dozens of costly mistakes.

Lossy Compression

Lossy compression permanently discards data to achieve smaller file sizes. The encoder analyzes the image and throws away information that the human visual system is least likely to notice: subtle color gradients, fine detail in shadowed areas, high-frequency texture in backgrounds. Once that data is gone, it cannot be recovered. JPEG, lossy WebP and lossy AVIF all work this way.

The trade-off is remarkable: lossy compression typically achieves 60-90% file size reduction compared to the raw uncompressed image. A 5.9 MB raw bitmap becomes a 350 KB JPEG. For photographs displayed on a screen, this is usually an excellent deal - the discarded data falls below the threshold of human perception at normal viewing distances.

Lossless Compression

Lossless compression shrinks a file while preserving every single pixel perfectly. When you decompress a lossless image you get a mathematically identical copy of the original. PNG, lossless WebP and GIF are all lossless formats. The compression works by finding and eliminating redundancy in the data: long runs of the same color, repeating patterns, predictable pixel sequences, rather than discarding anything.

The cost is file size: lossless compression delivers only a 20-40% reduction compared to raw data and photographs (which have very little pixel-to-pixel redundancy) compress especially poorly. A lossless PNG of a full-resolution photograph is often 10× larger than an equivalent JPEG.

When Lossless Matters

• Text and logos: lossy artifacts create visible halos around sharp letter edges
• Line art and diagrams: hard edges amplify JPEG blocking artifacts
• Screenshots of user interfaces: small pixel patterns like 1px borders look terrible after lossy compression
• Images you will re-edit: each lossy save compounds the quality loss; keep masters lossless
• Transparency: images with complex alpha channels need per-pixel precision

For everything else (photographs, marketing imagery, hero banners), lossy compression is not just acceptable, it is the correct engineering choice. The goal is imperceptible quality loss at maximum compression and that is exactly what JPEG and WebP are engineered to deliver.

JPEG (Joint Photographic Experts Group) has been the dominant format for photographic images since 1992. Its longevity is not an accident: it is exceptionally well-suited to photographs and its 100% browser and device support makes it the universal fallback for digital imagery.

How JPEG Compression Works

JPEG uses Discrete Cosine Transform (DCT) compression. The image is split into 8×8 pixel blocks. Each block is transformed from the spatial domain (pixel brightness values) into the frequency domain (how much the brightness changes across the block). High-frequency components (fine detail, sharp edges) are then rounded more aggressively than low-frequency components like broad color areas. This rounding step, called quantization, is where the quality slider has its effect. Lossy JPEG also applies chroma subsampling (4:2:0), reducing color resolution to one-quarter while keeping full brightness resolution, because the human eye is far more sensitive to brightness changes than color changes.

Quality Settings in Practice

The quality number (1-100) controls how aggressively the quantization step rounds off frequency coefficients. It is not a linear scale: the differences between quality 85 and 95 are much smaller than the differences between 50 and 60.

Quality Setting	Typical File Size (4 MP photo)	Visual Result
95	1.2 MB	Near-lossless, professional archival
85	600 KB	Excellent - indistinguishable to most people
70	350 KB	Good - minor artifacts on close inspection
50	200 KB	Acceptable for thumbnails, visible artifacts
30	120 KB	Obvious blocking and mosquito noise

When to Use JPEG

• Photographs with complex gradients and natural texture
• Images where a small, imperceptible quality loss is acceptable
• Email attachments (universal client support)
• Legacy systems or software that may not support WebP/AVIF

When NOT to Use JPEG

• Text and logos: DCT artifacts create visible halos around crisp letterforms
• Images with transparency: JPEG has no alpha channel support at all
• Images you will re-edit and re-save: each save-cycle compounds quantization loss (generational degradation)
• Screenshots of UI: 1px lines and sharp contrasts become blurry smears

Progressive JPEG is a variant that encodes the image in multiple passes: a blurry low-resolution pass loads first, then successive passes sharpen the image. This gives a better perceived loading experience for large images over slow connections and is worth enabling for any full-width hero image larger than 200 KB.

PNG (Portable Network Graphics) was created in 1996 as a patent-free replacement for GIF. It is the correct format whenever pixel-perfect reproduction and transparency support are non-negotiable.

How PNG Compression Works

PNG uses DEFLATE compression (the same algorithm inside ZIP files), which combines LZ77 (finds repeated byte sequences) and Huffman coding (assigns shorter bit patterns to more-frequent symbols). Before DEFLATE, PNG applies a filter pass that transforms each row of pixel data to make it more compressible. The most effective filter (Paeth predictor) subtracts each pixel from its predicted value based on its neighbors, producing a stream of small numbers and zeros that DEFLATE can compress very efficiently. The entire pipeline is mathematically reversible, which is why PNG is lossless.

PNG Variants

• PNG-8: palette-based, maximum 256 colors (like GIF), much smaller than PNG-24 for simple graphics
• PNG-24: full 16 million colors, no transparency channel
• PNG-32: PNG-24 plus a full 8-bit alpha transparency channel per pixel

File Size Reality Check

Image Type	Format	File Size
2560×1440 screenshot	PNG-32	1.8 MB
2560×1440 screenshot	PNG-8	400 KB
2560×1440 screenshot	JPEG q85	350 KB (with artifacts on text)
4 MP photograph	PNG-24	12-18 MB
4 MP photograph	JPEG q85	600 KB

The photograph row above illustrates the core weakness of PNG for photographic content: it is 15-25× larger than JPEG for the same visual quality because natural photographs contain enormous pixel-to-pixel variation that DEFLATE cannot compress efficiently.

When to Use PNG

• Logos and brand marks: sharp vector-like edges reproduced perfectly
• Screenshots and screen recordings: text remains crisp
• Graphics containing text overlays
• Icons (though SVG is usually superior for scalable icons)
• Images with transparency on complex backgrounds: the alpha channel gives per-pixel opacity
• Master files for re-editing: no generational quality loss

Use the PNG to WebP converter to shrink PNG files by 26% on average while retaining lossless quality or gaining transparency support in a smaller package.

WebP was developed by Google, released in 2010 and became a practical web standard around 2020 when Safari finally added support. It is the single most impactful format change most websites can make today: nearly universal browser support combined with meaningfully smaller files than both JPEG and PNG.

Two Modes: Lossy and Lossless

Lossy WebP is based on the VP8 video codec's intra-frame prediction algorithm. Key improvements over JPEG: it uses larger transform blocks (up to 16×16 instead of JPEG's fixed 8×8), which reduces block-boundary artifacts; it uses arithmetic entropy coding instead of Huffman coding for better compression efficiency; and it includes an in-loop deblocking filter that smooths block edges during decoding. The result: 25-35% smaller files than JPEG at equivalent visual quality.

Lossless WebP uses a proprietary algorithm (not DEFLATE) specifically designed for image data. It achieves approximately 26% smaller files than PNG for the same pixel-perfect output. It supports full alpha transparency, just like PNG-32.

Unique Capabilities

• Alpha transparency: full 8-bit alpha channel in both lossy and lossless modes, unlike JPEG
• Animation: supports multi-frame animation (like GIF but with far better compression and color depth)
• ICC color profiles and Exif/XMP metadata support

Browser Support

As of 2026, WebP is supported by 96%+ of global browser users. All major browsers have supported it since: Chrome 23+ (2012), Firefox 65+ (2019), Edge 18+ (2019), Safari 14+ on macOS Big Sur and iOS 14 (2020). The only meaningful exceptions are Internet Explorer (effectively dead, <1% share) and some older embedded browser environments.

When to Use WebP

• Any image displayed on a website - it is the sensible default for web in 2026
• Replacing JPEG for photographs (smaller, same quality)
• Replacing PNG for UI graphics that need transparency (smaller than PNG)
• Animated content (superior to GIF in every measurable way)

One caveat: WebP is not supported in most email clients (Outlook, older Apple Mail versions), so continue using JPEG for email newsletter images. Very old browser versions (predating 2018) may lack WebP support, but these represent a negligible share of real-world traffic. Use the JPG to WebP converter or PNG to WebP converter to make the switch quickly.

AVIF (AV1 Image File Format) is the newest format in this comparison and arguably the most technically impressive. It is based on the AV1 video codec, a royalty-free format developed by the Alliance for Open Media (a consortium including Google, Apple, Microsoft, Netflix and Amazon) specifically to push the boundaries of compression efficiency.

Why AVIF Compresses So Well

AV1's compression engine was designed to encode 4K HDR video efficiently, which means it has sophisticated tools for representing complex spatial information. When applied to still images, these tools produce startling results: AVIF typically achieves 40-50% smaller files than JPEG at the same perceptual quality and 30% smaller files than WebP. At low-to-medium quality settings, AVIF's artifacts are also more natural-looking (film-grain-like) rather than the harsh blocking artifacts of JPEG.

Technical Capabilities

• HDR support: native 10-bit and 12-bit color depth for high dynamic range content
• Wide color gamut: supports Display P3 and Rec. 2020 color spaces
• Alpha transparency: full per-pixel alpha channel
• Animation: multi-frame support like WebP
• Lossless mode: mathematically perfect preservation

Browser Support (2026)

Browser	AVIF Support Since
Chrome	Version 85 (August 2020)
Firefox	Version 93 (October 2021)
Safari	Version 16 (September 2022)
Edge	Version 121 (January 2024)

Global AVIF browser support sits at approximately 85-90% in 2026. Safari's late adoption (2022) is the main reason that number isn't higher. For most web projects, serving AVIF with a WebP fallback via the <picture> element captures the compression benefit for modern browsers while maintaining compatibility everywhere else.

When to Use AVIF

• Hero images and above-the-fold photography where maximum compression matters most
• Product images on e-commerce sites (large image counts multiply savings)
• High-fidelity images that need HDR or wide-gamut color
• Any situation where you can serve AVIF with a WebP/JPEG fallback

Current limitation: AVIF encoding is significantly slower than JPEG or WebP: 5-20× slower per image. This matters for build pipelines processing thousands of images, but is irrelevant for on-demand conversion. Some CDNs are also still adding AVIF support to their image transformation pipelines.

Use this reference table when choosing a format for any project. "Typical size vs JPEG" refers to an equivalent-quality photographic image; results for non-photographic content will vary.

Format	Compression Type	Typical Size vs JPEG	Transparency	Animation	Browser Support	Best Use Case
JPEG	Lossy	Baseline (1×)	No	No	100%	Photographs, email, legacy systems
PNG	Lossless	3-20× larger	Yes (8-bit alpha)	No	100%	Logos, screenshots, text graphics
WebP	Lossy or Lossless	25-35% smaller	Yes (8-bit alpha)	Yes	~96%	All web images: the modern default
AVIF	Lossy or Lossless	40-50% smaller	Yes (full)	Yes	~88%	Hero images, product photos, HDR
GIF	Lossless (8-bit palette)	1-5× larger	Yes (1-bit only)	Yes	100%	Simple animation only (use WebP/AVIF instead)

Notes on the Table

• PNG's "3-20× larger" range reflects the difference between simple graphics (closer to 3×) and full-resolution photographs (up to 20× larger than JPEG)
• GIF's 1-bit transparency means a pixel is either fully transparent or fully opaque: no soft edges or semi-transparent shadows
• WebP and AVIF lossless modes compare favorably to PNG: WebP lossless is ~26% smaller than PNG; AVIF lossless is competitive on photographic content but slower to encode
• Browser support figures are global averages from Can I Use data as of early 2026 and shift upward each month as old browser versions age out

Work through these decision points in order to select the right format for any specific image.

Decision Tree

• Does the image require a transparent background?
  • Yes → Use WebP (best compression with alpha), or PNG (maximum compatibility), or AVIF (if modern-browser-only is acceptable)
  • No → Continue to next question
• Is it a photograph for a website?
  • Yes, targeting modern browsers → Use AVIF with a WebP fallback in a <picture> element
  • Yes, need broad compatibility → Use WebP (96% support, no fallback needed)
  • No → Continue
• Is it a logo, icon, or brand graphic?
  • Scalable (multiple sizes) → Use SVG (vector, infinitely scalable, tiny file)
  • Raster only → Use PNG (lossless crispness)
• Is it a screenshot or image containing text?
  • Yes → Use PNG. Lossy artifacts on text edges are unacceptable
• Is it for an email newsletter?
  • Yes → Use JPEG. WebP and AVIF are not supported in Outlook and most email clients
• Is it for uploading to social media (Instagram, Twitter/X, Facebook)?
  • Yes → Use JPEG at quality 85-90. Platforms recompress all uploads to their own format anyway, so starting format matters less than starting quality
• Is maximum browser/device compatibility absolutely required?
  • Yes → Use JPEG (photographs) or PNG (graphics)

Quick Summary by Scenario

Scenario	Recommended Format
Website hero image (photo)	WebP or AVIF+WebP fallback
Company logo on website	SVG (preferred) or PNG
Product photos (e-commerce)	AVIF + WebP fallback
Email newsletter image	JPEG
Social media upload	JPEG quality 90
App icon / UI asset	PNG or SVG
Screenshot with text	PNG
Animated banner	WebP animation or AVIF animation
Print-ready image	TIFF or JPEG quality 95+

At some point you will need to convert images between formats: either to optimize for web delivery, restore compatibility with a legacy system, or extract a copy for editing. Understanding the quality implications of conversion prevents nasty surprises.

Common Conversion Scenarios

• JPEG → WebP (the most common web optimization task): Use the JPG to WebP converter. Target quality 80-85 in WebP to match the visual quality of a JPEG at quality 85. You will typically see 25-35% file size reduction with no perceptible quality difference.
• PNG → WebP: Use the PNG to WebP converter. For logos and graphics, use WebP lossless mode to preserve crispness. For photographic PNGs, WebP lossy at quality 85 cuts the file to a fraction of the PNG size.
• WebP → JPEG: Use the WebP to JPG converter when sharing images via email, uploading to legacy software, or sending to clients who can't open WebP. If the WebP source was lossy, the conversion introduces a second round of lossy compression - keep the quality high (90+) to minimize compounding artifacts.
• PNG → JPG: Use the PNG to JPG converter when a PNG photograph needs to be shrunk significantly and transparency is not required. Expect 80-90% size reduction.

The Re-Encoding Problem

Converting between two lossy formats (especially JPEG to JPEG) degrades quality each time. The original JPEG already has quantization artifacts baked in. When you open and re-save it as a JPEG, the encoder runs its quantization step again over already-degraded data. Do this five times and the artifacts become obvious even at quality 85. This is called generational loss.

The rule: always convert from the highest-quality source available. If you have the original camera RAW file or a high-resolution TIFF, convert from that rather than from a previous JPEG export. If you only have a JPEG, convert it to your target format once, at the highest acceptable quality and preserve that derivative as your new archival copy.

When Format Conversion Won't Help

Converting a low-quality JPEG (quality 50, obvious artifacts) to WebP or AVIF will produce a smaller file, but the original artifacts are already embedded in the pixel data and will remain visible, or in some cases become slightly more visible because the new codec's compression pattern interacts with the existing JPEG patterns. There is no format conversion that recovers discarded lossy data. The only solution is to return to the original source and re-export at higher quality. Use the image compressor to find the optimal quality setting before committing to a final export.