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Image conversion

Convert and resize images between PNG, JPEG, WebP, AVIF

Convert an image to PNG, JPEG, WebP or AVIF (where the browser supports it), with quality control and optional resizing. See the before and after file size at once to pick the best trade-off between weight and quality. Conversion happens via canvas in the browser: the image is never uploaded to any server and never leaves the device.

Drop an image here or click
PNG, JPG, WebP, GIF, BMP. The image stays in the browser.

How to convert an image

  1. 1

    Load the image

    Drop the file into the drop zone or click to select it. Common image formats the browser can decode are accepted.

  2. 2

    Choose format and quality

    Pick the target format (PNG lossless, JPEG/WebP/AVIF with adjustable compression). For lossy formats, tune the quality to balance weight and look.

  3. 3

    Resize if needed

    Set a maximum width to reduce the pixel dimensions while keeping the aspect ratio. Leave 0 to keep the original resolution.

  4. 4

    Convert and download

    Run the conversion: you will see the before and after size and the final dimensions. Download the file with one click. Everything stays in the browser.

Which format to choose and how it works

Conversion uses the browser canvas: the image is decoded, drawn onto a graphics surface and re-exported in the chosen format via canvas.toBlob. The result is therefore always a rasterised (pixel) image: you can change format, quality and dimensions, but you cannot recover vector information or layers the source did not expose as pixels.

The format choice depends on the use. PNG is lossless and handles transparency: ideal for graphics, logos, screenshots with crisp text, but heavier. JPEG is lossy and great for photographs, where a few artefacts are invisible and the weight drops, but it has no transparency. WebP offers both lossy and lossless modes, with files usually lighter than JPEG and PNG at the same quality, and is now supported everywhere. AVIF compresses even better, but it is slower to encode and not every browser can export it: where it is unsupported, the tool tells you.

Quality only matters for lossy formats (JPEG, WebP, AVIF): high values preserve detail but weigh more, low values lighten the file while adding artefacts. Resizing acts on the pixel count and is often the most effective way to cut the weight of a photo bound for the web. Everything happens in the browser: no upload, useful for confidential images you do not want passing through a third-party server.

Glossary

Technical terms used on this page, briefly explained.

Lossy format #
A format (JPEG, WebP, AVIF) that cuts weight by discarding hardly-perceptible information. Quality is adjustable: more compression, more artefacts.
Lossless format #
A format (PNG, lossless WebP) that keeps every pixel exactly. Heavier files but no degradation, suited to graphics and text.
Canvas #
The browser drawing surface. The tool draws the image onto it and re-exports it in the chosen format via toBlob, all locally.
WebP #
A modern Google format, lossy or lossless, usually lighter than JPEG and PNG at the same quality. Supported by all recent browsers.
AVIF #
A format based on the AV1 codec, with excellent compression but slower encoding and non-universal export support across browsers.
Transparency (alpha channel) #
Per-pixel opacity information, present in PNG, WebP and AVIF but not in JPEG. Converting to JPEG makes transparent areas opaque.

Image conversion FAQ

Is the image uploaded to a server?
No. It is decoded and re-exported on the browser canvas. No file is sent. You can verify it in the Network tab of the developer tools, or use the tool offline after loading the page.
Why does AVIF sometimes not work?
Because not every browser supports AVIF export via canvas, even if it can display it. When your browser cannot generate the chosen format, the tool tells you: in that case use WebP, which is just as efficient and supported everywhere.
Does converting to JPEG lose transparency?
Yes. JPEG does not support the alpha channel, so transparent areas become opaque (usually on a white or black background). If you need transparency, choose PNG, WebP or AVIF.
How do I minimise a photo's weight?
Two levers: reduce the pixel dimensions (max width) and use an efficient lossy format (WebP or AVIF) at medium quality. For web photos, resizing alone often matters more than quality in the final result.
Does quality affect PNG?
No. PNG is lossless: the quality slider has no effect on it. It only matters for JPEG, WebP and AVIF. To lighten a PNG, the only lever here is resizing.
Can I convert several images at once?
The tool works on one image at a time, to keep the weight and quality comparison clear. For bulk conversion of many images, a dedicated command-line tool is better.
Does conversion reduce quality?
It depends. Towards a lossless format (PNG) at full resolution nothing is lost. Towards a lossy format or when resizing, some information is discarded: the tool shows the resulting weight so you can pick the trade-off you prefer.

Who builds these tools?

Maurizio Fonte, senior IT consultant with 20+ years in PHP, Laravel, unmanaged Linux infrastructure, applied cybersecurity and AI/LLM integration. Production backends, legacy code modernization, security audits, custom AI agents and MCP servers: the work behind every tool published here.

About Maurizio Fonte