Which image format should you use?

Photographs go to JPEG or WebP. Screenshots, logos, diagrams and anything with sharp edges or flat colour go to PNG. If you need transparency and a small file, WebP does both.

That covers almost every decision. The rest of this page explains why, so you can tell when the rule does not apply — and what to do about AVIF and HEIC, which browsers handle much less consistently than the other three.

Last reviewed: 2026-09-19. Checked against the tool’s own source on that date.

JPEG

JPEG divides the picture into blocks and discards the fine detail your eye is least likely to notice. That works extremely well on photographs, where detail is irregular and noisy, and badly on anything with hard edges, where the discarded detail is exactly what defines the edge.

It is lossy at every quality setting, including the highest. There is no lossless JPEG option here. It cannot store transparency: an image with transparent areas gets them filled with a solid colour when it becomes a JPEG.

Use it for: photographs, scans of photographs, any picture that is mostly continuous tone. Avoid it for: screenshots, text, line art, logos, and anything that will be edited again later.

PNG

PNG is lossless. It stores exactly the pixels it was given, so it never introduces artefacts, and it supports full alpha transparency. Its compression exploits repetition, which is why it is dramatically efficient on flat colour and sharp edges, and inefficient on photographic noise.

A photograph saved as PNG is typically several times larger than the same photograph as JPEG, with no visible benefit. This is the single most common image-format mistake and it is worth checking for before blaming a slow page on anything else.

Use it for: screenshots, UI captures, logos, diagrams, charts, anything with text in the picture, and any working copy of an image you intend to edit again.

WebP

WebP is usually the smallest of the three at a comparable visual quality, and it supports transparency, which makes it the one format that covers both jobs.

One caveat that matters here: your browser encodes WebP in lossy mode even at quality 100. The format does define a lossless mode, but the canvas API this tool uses does not expose it. So a WebP export from this site is a lossy export, and it is described that way rather than being called lossless because the format supports it in principle.

Browser support for displaying WebP is effectively universal now. Support for encoding it is not quite as uniform, so a browser that cannot encode WebP reports an error here rather than quietly handing you a different format.

AVIF and HEIC — the honest position

AVIF compresses better than all three formats above, often substantially. HEIC is what modern iPhones use for photographs by default. Neither can be read by the ToolAcre Image Converter, and that is a browser limitation rather than a choice.

Browsers can usually DISPLAY AVIF, but they do not expose a reliable way to decode arbitrary AVIF or HEIC files for processing, and HEIC decoding in particular depends on a platform codec that is not present everywhere. A tool that accepted these files would work on some machines and fail confusingly on others, so they are rejected clearly instead.

The practical consequence: convert HEIC to JPEG on the device that produced it — every current phone and both major desktop operating systems can do this — and then use browser tools on the JPEG. For AVIF, keep a JPEG or PNG master and generate AVIF as an output at publish time with a build tool.

A note on GIF

GIF is limited to 256 colours per frame and is a poor choice for anything except short animations. The Image Converter reads GIF but uses only the first frame, and does not offer GIF as an output — producing a still image with a .gif extension would be misleading rather than helpful.

For a short animation, the modern answers are an MP4 or WebM video, or an animated WebP. None of those are produced here.

Worked example: four assets for one article

An article needs a hero photograph, a screenshot of an interface, a logo with a transparent background, and a chart exported from a spreadsheet.

  • Hero photograph — JPEG at the default quality, resized to about twice its display width. Continuous tone, no transparency needed.
  • Interface screenshot — PNG. It is full of text and hard edges, exactly what JPEG handles worst, and PNG compresses its flat panels efficiently.
  • Logo — WebP or PNG. Both keep transparency; WebP will be smaller, PNG will be exact. For a logo that will be placed on varying backgrounds, exactness is worth more than a few kilobytes.
  • Chart — PNG. Same reasoning as the screenshot: flat fills, thin lines and axis labels.

Result: Four files, three formats, each chosen by what is in the picture rather than by habit. The commonest failure mode — exporting all four as PNG, or all four as JPEG — makes either the photograph several times too large or the screenshot and chart visibly smeared around their text.

Open the tool

Convert between JPEG, PNG and WebP

The Image Converter states whether a conversion is lossy before you run it, and reports real measured sizes afterwards.

What this does not cover

  • The ToolAcre Image Converter reads JPEG, PNG, WebP and GIF, and writes JPEG, PNG and WebP. HEIC, AVIF, TIFF and camera RAW are rejected.
  • WebP output from this site is lossy, because that is what the browser canvas API exposes.
  • Colour profiles are not preserved through a canvas conversion, so images with an unusual embedded profile may shift slightly.
  • File size comparisons depend on the picture. Any rule of thumb here is a starting point to measure from, not a number to quote.