PNG Converter

Produce lossless PNGs with a clean alpha channel. Up to 5 images per batch.

Drag & drop images here

or tap to browse (PNG, JPEG, WebP, SVG)

Up to 5 images per batch, 25 MB each

Target Format

png

Up to 5 images per batch

Add up to five images

JPEG, WebP and PNG sources are all accepted. Each is verified by its header bytes and checked against the 25 MB and 8192 pixel limits before it joins the batch.

Tip: Converting a JPEG to PNG will not undo JPEG compression. It preserves the artefacts perfectly instead of removing them.

Set any crop or scale you need

Cropping and scaling happen on the decoded bitmap before the PNG is written, so the output is exactly the dimensions you asked for with no resampling afterwards.

Tip: Scale down in one step rather than repeatedly. Each resample softens edges a little.

Process and download

Output is bundled into a ZIP with original filenames. The quality slider has no effect here because PNG is lossless and has no quality parameter.

Tip: If the resulting files feel too big, that is PNG working correctly. Use the WebP tool when size is what you care about.

Genuinely lossless

Every pixel comes back bit for bit identical. There is no quality setting to get wrong and no generational loss if you convert the same file repeatedly through an editing workflow.

Full 8-bit alpha

Soft shadows, feathered cut-outs and anti-aliased edges composite cleanly against any background colour, which is what separates PNG from the indexed transparency GIF offered.

Ideal for flat colour and text

The row prediction filters ahead of DEFLATE make PNG unusually good at long runs of identical colour and hard edges, exactly the content that lossy formats ring and blur around.

Nothing is uploaded

PNG encoding runs through the browser canvas inside a Web Worker. The tool works with the network disconnected and no part of your image is transmitted to any server.

Five per batch

Decoded bitmaps are large regardless of file size, and PNG output buffers are larger still. Holding the batch at five keeps memory predictable on laptops and phones alike.

Still universally supported

Every browser, operating system, office suite and image editor written in the last twenty-five years reads PNG. When something has to open anywhere with no negotiation, this is the format.

Frequently Asked Questions

Will converting a JPEG to PNG improve its quality?+

No, and this is the most common misunderstanding about the format. PNG preserves exactly what it is given. Converting a JPEG to PNG stores that JPEG's compression artefacts losslessly and produces a much larger file containing the same visible image.

Why does the quality slider do nothing on this page?+

Because PNG has no lossy quality parameter. Its compression is entirely lossless, so the only levers are the prediction filter and the DEFLATE level, neither of which changes what the image looks like.

When should I pick PNG over WebP?+

When you need the exact pixels back, when the file is going into further editing, or when it has to open in something old or unusual. For anything being served to a browser as a final asset, lossless WebP is smaller and does the same job.

Does PNG support animation?+

APNG exists and browsers support it, but it is an extension rather than part of the base specification, and this tool does not produce it. Still images only.

Why are my PNG files so large?+

Almost certainly because the content is photographic. DEFLATE cannot find repeating patterns in photographic noise, so it stores nearly all of it. That is the format behaving correctly rather than a fault.

If size matters more than exactness for that image, the WebP or AVIF tools will produce something dramatically smaller.

Can I convert five at a time and repeat?+

Yes. The limit applies to a single batch. Clear the queue, load the next five and go again. There is no session quota because there is no server keeping count.

Format Comparison

Feature Specification	PNG conversion	Alternative
Fidelity	Bit-for-bit identical	Approximate
Typical size, photograph	5 to 10 times larger	Baseline
Typical size, flat graphics	Often smaller	Larger, with edge ringing
Transparency	Full 8-bit alpha	None
Best suited to	Screenshots, logos, exact-pixel work	Photographs

Technical Overview & Specifications

Deep dive into PNG conversion architecture and processing.

Show Details

Platform Overview

PNG exists because GIF was patented and limited to 256 colours, and the web needed something better in a hurry. What the working group produced in 1996 has aged remarkably well. PNG stores every pixel exactly as it was given, supports up to 16 bits per channel, and carries a proper 8-bit alpha channel rather than the single transparent colour index GIF offered. It compresses with DEFLATE after running each row through one of five prediction filters, which is why it does so well on flat colour and hard edges and so badly on photographs. Nothing about it has been deprecated, nothing has replaced it for its actual job, and it will still be decoding correctly long after the current crop of formats has been superseded.

Convert to PNG when you need the pixels back unchanged. That covers line art and icons, diagrams with thin strokes or small text, screenshots destined for documentation where compression artefacts would be embarrassing, images going into a further editing pass, and anything with transparency that has to composite cleanly against an unknown background. Do not convert photographs to PNG hoping for quality, because you already have whatever quality the source had and all you will gain is a file five to ten times larger. This tool takes five images per batch and does the whole job in your browser, so nothing is transmitted anywhere.

Why PNG compresses the way it does

PNG's compression happens in two stages. First each scanline is passed through one of five filters, which replace absolute pixel values with differences from the pixel to the left, the pixel above, an average of the two, or a Paeth predictor that picks whichever neighbour is closest. On an area of flat colour every difference becomes zero. On a smooth horizontal gradient every difference becomes the same small constant. The filtered data then goes through DEFLATE, which is very good at compressing long runs of identical bytes and much less impressive on anything resembling noise. This is the whole explanation for PNG's reputation: it is superb on graphics and poor on photographs, and both behaviours come from the same mechanism.

In this tool the encode is done by the browser's own PNG writer through the canvas API, running in a Web Worker with OffscreenCanvas. The source is decoded to an image bitmap, drawn into a canvas at the target dimensions with any crop applied, and serialised. Because there are no lossy parameters to tune, the only decisions that affect the output are the crop rectangle and the scale factor, which is why this page shows neither a quality slider nor a format selector. Browsers that lack OffscreenCanvas fall back to processing on the main thread, and the page displays a notice when that happens so a slow tab has an explanation rather than being a mystery.