WebP vs AVIF vs JPEG vs PNG: Which Image Format Should You Use and How Can You Reduce File Size?

In 2026, all four formats are still useful, but for different jobs:

• AVIF most often wins on transfer size for photographs and complex imagery.
• WebP provides an excellent balance of compression, features, compatibility and implementation cost.
• JPEG remains the safest fallback for photography and systems with unknown requirements.
• PNG is most useful for lossless raster graphics, interface screenshots, pixel-level detail and assets that require precise transparency.

TL;DR: for photography, serve AVIF first, WebP second and keep JPEG as the fallback. For screenshots, simple graphics and transparency, compare lossless WebP or AVIF against PNG. For icons and logos, SVG is usually a better choice than any of these raster formats.

Features, compatibility and recommendations were last verified on 23 July 2026.

The main differences at a glance

AVIF supports lossy and lossless compression, transparency, animation, HDR and wide colour gamut. WebP combines lossy and lossless modes, alpha transparency and animation. PNG is lossless and supports partial alpha transparency, but usually creates excessive transfer sizes for photography.

The quickest answer: which format should you choose?

Do not impose one format on every image. The best result comes from a policy based on asset type, not from a rule that says “convert everything to AVIF”.

1. JPEG: still useful, but rarely the best primary format

JPEG was designed for photographs. It uses lossy compression, discarding information that is less noticeable to human vision. This makes photographs far smaller than lossless PNG files, but excessive compression produces visible blocks, colour shifts and missing detail.

Advantages of JPEG

• near-universal support across browsers, editors, CMS platforms and external services,
• a dependable fallback for photography,
• fast encoding and decoding,
• support for progressive JPEG,
• mature optimisation tooling such as MozJPEG.

A progressive JPEG initially displays a low-detail version across the full image and then becomes sharper as more data arrives. It can also be slightly smaller than baseline JPEG and may feel faster on a slow connection.

Limitations of JPEG

• no alpha channel,
• no animation,
• compression is lossy,
• sharp lines, text and interface elements acquire artefacts quickly,
• repeated saving and recompression reduce quality,
• WebP and AVIF often create smaller files at comparable visual quality.

An official WebP team study found WebP files 25-34% smaller than JPEG at a comparable SSIM score. This should not be treated as a guaranteed saving for every asset because the result depends on the source material, encoder version, settings and quality metric.

When should you use JPEG in 2026?

JPEG is a sensible choice when:

• one file must work in the broadest range of systems,
• you do not control the client receiving the image,
• the asset will be used in an older CMS, email, document or third-party platform,
• you need a fallback inside <picture>,
• your AVIF/WebP generation process is not ready.

This does not mean JPEG should be the primary format for every photograph on a new website. When you control the frontend, modern alternatives are usually worth serving first.

2. PNG: lossless quality, sharp detail and transparency at a cost

PNG uses lossless compression. Once decoded, it preserves pixel data without compression loss. It also supports an alpha channel with multiple transparency levels rather than only fully visible or fully transparent pixels.

Advantages of PNG

• excellent sharpness for text, lines and interface elements,
• full alpha transparency,
• no generational loss when saving again,
• universal compatibility,
• a useful reference format for simple raster graphics.

Limitations of PNG

• photographs are usually much larger than JPEG, WebP or AVIF,
• classic PNG is not an animation format; APNG is the animated variant,
• raster graphics do not scale as cleanly as SVG,
• unnecessary metadata, channels or poorly chosen palettes can increase size,
• keeping PNG solely because an image contains transparency is no longer always justified.

web.dev notes that PNG is almost never the right delivery format for photography because lossless storage leads to excessive transfer size. For simple semi-transparent graphics, it should be compared with WebP or AVIF.

When does PNG still win?

PNG is the best or safest option when:

• a screenshot contains small text and thin lines,
• you need a lossless raster copy,
• a platform accepts PNG but not WebP or AVIF,
• the graphic uses a small colour palette,
• exact reproduction matters more than transfer size,
• you need a source asset for later encoding.

For logos, icons, charts and simple illustrations, test SVG first. Vector files normally scale better and can be lighter than raster assets.

3. WebP: the most practical default format

Google originally developed WebP as a more efficient alternative to JPEG. Later versions added lossless compression, alpha transparency and animation, allowing it to replace JPEG photos, many PNG graphics and some GIF animations.

Advantages of WebP

• lossy and lossless modes,
• transparency,
• animation,
• broad support in current browsers,
• mature support in CMS platforms, libraries and image CDNs,
• usually smaller files than JPEG or PNG,
• simpler and often faster encoding than AVIF pipelines.

Limitations of WebP

• no progressive display,
• older software and some publishing workflows may still require JPEG or PNG,
• quality depends on the encoder and settings, and a “quality” number is not comparable across formats,
• WebP will not always beat a well-encoded AVIF,
• lossless WebP does not always beat an aggressively optimised PNG for every simple graphic.

When is WebP the best choice?

WebP is an ideal starting format when a team wants to:

• reduce photographs quickly without building a complex pipeline,
• preserve transparency,
• support nearly all current browsers with one modern variant,
• process images locally or on demand,
• limit the number of production formats,
• balance quality, file size and encoding cost.

The POLPROG Image Converter & Optimizer processes PNG, JPG and WebP locally in the browser and supports format conversion, compression, resizing and metadata removal.

4. AVIF: the smallest transfers and the broadest modern feature set

AVIF is based on the AV1 codec and HEIF container. It was designed as a modern raster image format and supports lossy and lossless compression, alpha transparency, animation, HDR and wide colour gamut.

Advantages of AVIF

• very high compression efficiency,
• strong visual quality at low bitrates,
• lossy and lossless modes,
• transparency and animation,
• 8-, 10- and 12-bit images and HDR,
• support in all current major browsers,
• particularly strong results for photographs, gradients and complex imagery.

AVIF has been a Baseline feature since January 2024, meaning current versions of the major browser engines support it.

Limitations of AVIF

• no progressive display: the image generally needs to download before it can be shown,
• encoding may require more compute than JPEG or WebP,
• output size and quality depend heavily on encoder, speed, chroma subsampling and settings,
• some external systems may still reject .avif uploads,
• tiny graphics and simple icons may not be smaller than SVG, PNG or WebP,
• poorly configured AVIF can blur texture or small text.

MDN notes that AVIF may offer slightly better compression than WebP but does not support progressive rendering. Do not budget around a fixed promise such as “AVIF is always 50% smaller”. The difference depends on the asset and encoding parameters.

When should AVIF be deployed?

AVIF makes the most sense when:

• images account for a large part of page transfer,
• the website contains many product or hero photographs,
• the team has an automated image pipeline,
• assets are encoded once and delivered many times,
• HDR, wide colour gamut or higher bit depth matters,
• WebP/JPEG can be retained as fallbacks.

5. Is AVIF always smaller than WebP?

No.

In many comparisons AVIF achieves a better quality-to-size ratio than WebP and JPEG, and web.dev identifies it as the strongest choice for photographic collections, with WebP as a modern fallback and JPEG as the most reliable default. However, the output for one image depends on:

• image content,
• resolution,
• noise,
• text and thin lines,
• lossy or lossless mode,
• bit depth,
• chroma subsampling,
• encoder implementation and version,
• speed settings,
• the selected quality metric.

Compare formats at equivalent visual quality, not at the same slider value. quality=75 in JPEG, WebP and AVIF does not represent the same quality or compression strength.

6. Image format, Core Web Vitals and LCP

A modern format can reduce resource transfer time and therefore improve the download-related part of LCP. It cannot fix late image discovery, a slow server, incorrect dimensions or JavaScript-controlled rendering.

For an LCP image:

• do not use loading="lazy",
• place it in HTML as early as practical,
• consider fetchpriority="high",
• provide correct width and height,
• deliver the right resolution with srcset and sizes,
• avoid redirects and unnecessary dependencies,
• do not download multiple unused variants.

web.dev recommends that above-the-fold images, especially LCP candidates, should not be lazy-loaded. fetchpriority="high" can help the browser assign appropriate priority earlier.

For a broader checklist, see Website Audit in 2026 and Core Web Vitals in Practice.

7. Correct AVIF, WebP and fallback implementation

The most predictable pattern uses <picture>:

<picture>
  <source
    type="image/avif"
    srcset="/images/hero-800.avif 800w,
            /images/hero-1280.avif 1280w,
            /images/hero-1920.avif 1920w"
    sizes="100vw"
  >
  <source
    type="image/webp"
    srcset="/images/hero-800.webp 800w,
            /images/hero-1280.webp 1280w,
            /images/hero-1920.webp 1920w"
    sizes="100vw"
  >
  <img
    src="/images/hero-1280.jpg"
    srcset="/images/hero-800.jpg 800w,
            /images/hero-1280.jpg 1280w,
            /images/hero-1920.jpg 1920w"
    sizes="100vw"
    width="1920"
    height="1080"
    fetchpriority="high"
    alt="Website performance analysis dashboard"
  >
</picture>

The browser selects the first supported <source>, so AVIF should appear before WebP and the regular <img> provides the fallback.

Google can discover an image from the src attribute of <img>, including when that element is inside <picture>. Google Search supports JPEG, PNG, WebP and AVIF.

Images below the fold

For off-screen images:

<img
  src="/images/example.webp"
  width="960"
  height="640"
  loading="lazy"
  decoding="async"
  alt="Image file-size comparison"
>

Do not add loading="lazy" mechanically to every image. Hero images, main product images and LCP candidates should be discovered and fetched early.

8. Responsive images matter more than format alone

Converting a 2400 × 1600 image to AVIF does not solve the problem if a phone displays it at 360 pixels wide. Serving the correct pixel count can save more than changing the codec.

Always consider:

• width variants in srcset,
• correct sizes,
• separate mobile crops where composition requires them,
• high pixel density only where users can see the benefit,
• maximum upload dimensions in the CMS,
• generating thumbnails rather than scaling a full-size source in CSS.

Format, dimensions and compression level should be treated as one system.

9. How should quality be compared without misleading conclusions?

Do not compare kilobytes alone. A sound process is:

1. Start with the best available source, preferably original or lossless.
2. Generate several quality levels for each format.
3. Review files at the final display size.
4. Inspect faces, hair, gradients, text, edges and dark areas.
5. Measure encoding and decoding cost in the real environment.
6. Choose the smallest file that preserves acceptable quality.
7. Repeat the test for different classes of imagery.

Metrics such as SSIM can help automate comparison, but they should not replace visual inspection. Two files with similar numeric scores may look different to a user.

10. Common image optimisation mistakes

Converting from an already heavily compressed JPEG

The best results come from the original or a lossless source. Encoding AVIF from a poor JPEG cannot restore missing detail and may preserve existing artefacts.

One quality value for every image

A portrait, screenshot, night photograph and gradient illustration respond differently to compression. Automation should use profiles or quality checks.

Missing dimensions in HTML

Missing width and height can cause CLS whether the file is AVIF, WebP, JPEG or PNG.

Lazy-loading the hero image

A small AVIF can still load too late if the browser discovers it only after rendering or it receives loading="lazy".

Generating every possible variant

Many widths across four formats can significantly increase storage and build time. Observe real usage and generate only useful variants.

Using PNG for every transparent asset

WebP and AVIF support alpha transparency too. Keep PNG when it produces better edge quality, a smaller result for a particular asset or is required by a platform.

Using raster files for icons and logos

SVG is usually better for simple interface assets: it scales without losing quality and can be styled.

11. Image SEO: format is only one part

Google Search supports all four formats discussed here. Google does not document a ranking bonus simply for using .avif or .webp. The likely benefit is indirect: lower transfer size can improve performance and user experience.

Also ensure:

• a descriptive, stable file URL,
• extension matching the real file type,
• correct MIME type,
• useful alternative text,
• visible text context around the image,
• crawler access,
• correct dimensions,
• an image sitemap for image-heavy websites,
• licence metadata where relevant.

Use Website Health Check for performance and technical checks, and validate social-sharing graphics with Open Graph Preview.

12. Recommended image policy for a new website

Simple option

For a small website:

• WebP as the primary format,
• JPEG fallback for photographs,
• PNG only for selected graphics,
• SVG for logos and icons,
• srcset for important images.

Optimal option

For high-traffic or image-heavy services:

• AVIF first,
• WebP second,
• JPEG fallback,
• lossless WebP/AVIF or PNG for screenshots,
• automatic width variants,
• quality and transfer budgets,
• LCP and RUM monitoring after deployment.

E-commerce option

• product photography in AVIF and WebP,
• JPEG fallback,
• separate large and thumbnail variants,
• load the zoom image only after interaction,
• do not lazy-load the critical product image,
• test fine textures, colour and transparency,
• use caching and an image CDN.

Final verdict

AVIF is the best choice when minimum transfer is the priority and you have a strong pipeline. WebP is the best general-purpose format when simplicity, compatibility and strong compression matter. JPEG remains the safest photographic fallback, while PNG should be used deliberately for lossless graphics and transparency.

The best strategy in 2026 is not “pick one format”. It is:

AVIF → WebP → JPEG

for photographs, and:

lossless AVIF/WebP ↔ PNG

for assets requiring sharp detail or transparency, after an actual quality and size comparison.