Should I Use WebP, AVIF, JPEG or PNG Images?

There is no single image format that is best for every website asset. Choose according to the picture, required transparency, acceptable quality and the browsers or tools that must use it.

WebP and AVIF are useful modern options, but changing an extension alone does not optimise a page. An oversized image in a newer format can still waste data.

Separate format from dimensions

Dimensions describe the number of pixels. Format describes how the image is encoded. Quality settings affect how much detail is retained during compression.

A 4000-pixel-wide photograph displayed in a small card may need resizing before the format decision becomes meaningful. Our compression guide explains how to compare useful detail at the intended size.

Keep the original master separately. Website delivery files should not become the only surviving copy of valuable photography.

Understand the common options

MDN’s image-format guide describes the capabilities and browser support of these formats. JPEG is a familiar lossy photographic format; PNG supports lossless raster images and transparency. WebP and AVIF offer modern compression options and support transparency, with compatibility considerations for the delivery context.

Those capabilities do not establish a universal saving percentage. Different pictures respond differently to different encoders and settings.

For simple vector logos, an appropriate SVG source may be a separate option. Do not convert every sharp graphic into a photograph-like raster merely to standardise the folder.

Run a small comparison with your own content

Choose three representative assets: a photograph, a graphic with sharp edges and an image requiring transparency.

Export suitable candidates at the same intended dimensions. Compare the actual file sizes and inspect details such as hair, fine foliage, gradients and lettering where present.

Record	Why it matters
Asset purpose	A decorative photo and technical diagram need different detail
Delivered dimensions	Keeps the comparison meaningful
File size	Measures the actual candidate, not an advertised average
Visible defects	Reveals whether savings damage useful information
Compatibility	Confirms the intended consumers can display it

This is a suggested test method, not a benchmark result. No format has won until you inspect the outputs.

Check more than the newest browser

The website may serve older devices, embedded browsers, email systems or social-preview crawlers. Confirm the requirements of each destination.

A developer can arrange suitable fallback delivery where needed. Keep those decisions in the image pipeline rather than asking every editor to remember technical compatibility rules.

For mobile visitors, the responsive-image guide explains why choosing the appropriate source size is a separate task from choosing the format.

Avoid repeated lossy conversions

When revising an image, return to a good source rather than repeatedly compressing an already compressed delivery file. Otherwise damage can accumulate even when each individual save looks modest.

Document the intended crop and retain enough source detail for later layouts. A thumbnail and a full-width article hero do not always need the same export.

Also keep meaningful alt text in the content system. A smaller file does not replace the need to communicate the image’s purpose.

Verify the page outcome

After the new assets are integrated, check that the browser downloads the expected files and that they render correctly at ordinary and high-density sizes.

Use the website speed guide to judge the whole page, not just one image’s byte count.

Choose an image format that delivers the picture clearly and reliably without unnecessary data. Check the result on the page before considering the work complete.

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