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ImageConverter

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Compress PNG

Make PNG files dramatically smaller — often 60–70% smaller — while keeping full transparency. It uses palette quantisation, something a browser cannot do on its own; the reason is explained below. Your file is processed and deleted immediately.

Deleted automatically Uploads removed within 30 minutes

Drag and drop your PNG images here

Add several at once. Each file is processed and then deleted from our server.

Up to 20 MB per file Batch ready

80
Smaller file More detail
Presets:

Higher keeps more detail; lower makes a smaller file. Applies to images you add after changing it.

Step by step

How to compress PNG images in 4 steps

  1. Add your PNG files

    Drag them in or click to browse.

  2. Set the quality ceiling

    80 is the default and is usually indistinguishable from the original on graphics and logos.

  3. Wait a moment

    Wait a moment while the file is processed. Each one reports how much smaller it became.

  4. Download

    Your file is removed from our server as soon as you have it, and automatically within half an hour if you never do.

Good to know

How PNG compression works

PNG compression works completely differently from JPEG, and that difference is why this tool exists at all.

PNG is lossless. It reduces file size by finding patterns — runs of identical pixels, rows similar to the row above — and describing them compactly. It never discards information, which is why a PNG re-saved a hundred times is identical to the original.

The consequence is that there is no quality dial. You cannot ask a PNG encoder for "80% quality" the way you can with JPEG, because it has no mechanism for throwing detail away. Two PNGs of the same image look identical; only the encoder's effort differs, and that changes size by a few percent at best.

So how do you make a PNG substantially smaller? Palette quantisation. A full-colour PNG stores up to 16.7 million possible colours. Most images — logos, icons, illustrations, screenshots, diagrams — use only a few hundred distinct colours in practice. Reducing the image to an optimised palette of, say, 256 carefully chosen colours typically cuts the file to a third of its size, and on flat-colour graphics the difference is genuinely hard to see.

Transparency survives. Quantisation preserves the alpha channel, including partial transparency, so a logo with a soft shadow stays a logo with a soft shadow.

Quality

Choosing a compression level

The setting on this page is a ceiling for the palette reduction, not a JPEG-style quality. Higher values keep more colours and produce a larger, more faithful file.

  • 95–100 — Very close to the original. Use for photographs saved as PNG, and for images with subtle gradients.
  • 75–94 — The useful range for graphics. 80 is the default and is where most of the size saving comes from with no visible change.
  • 55–74 — Noticeably fewer colours. Fine for simple flat-colour icons; gradients start to show banding.
  • Below 55 — Visible posterisation, where smooth shading breaks into distinct bands. Rarely worth it.

What compresses well: logos, icons, UI screenshots, diagrams, charts, flat illustrations, anything with large areas of a single colour.

What does not: photographs. A photograph contains far too many distinct colours for quantisation to help without visible damage, and PNG was the wrong format for it in the first place. Convert to JPG or WebP instead — the saving will be far larger and the result will look better.

If a file comes back the same size, it was already optimised or has too few colours to reduce. We return the original rather than a larger file dressed up as a saving.

Why a browser cannot compress a PNG

Browsers expose exactly one way to produce a PNG: the canvas element. Canvas accepts a quality argument, but for PNG it ignores it — because PNG is lossless and there is nothing for a quality value to mean. A browser-based "PNG compressor" therefore re-encodes your image and hands back a file of essentially the same size, having achieved nothing.

Palette quantisation needs a proper quantiser. We use pngquant, which runs on our server.

PNG compression versus converting to WebP

Worth considering before you compress:

  • You must stay PNG — a tool, a platform or a client requires it. Compress here.
  • The image is for the web and you control the markup. WebP is almost always the better answer: smaller again and still transparent.
  • It is a photograph that happens to be a PNG. Convert to JPG or WebP; quantisation is the wrong tool.

Compressing several files

Add as many PNGs as you like — each is processed separately with its own download and size report. Because this runs on a shared server, the endpoint is rate limited, and very large batches are better done in groups.

Privacy

What happens to your file

This tool runs on our server, so it works the same on every phone and computer. Your file is uploaded, and this is exactly what happens to it:

  • Stored outside the public web root under a random name, never under your file's name.
  • Processed, with the original upload deleted immediately — whether it succeeded or failed.
  • The result sits behind a signed link that only you receive, which stops working after 20 minutes, and the file is deleted the moment you download it.
  • Anything never collected is deleted automatically within 30 minutes.
  • The image itself is never logged or kept. If a conversion fails, we record the formats involved and the error — not the file.
  • Camera metadata, including any GPS coordinates recording where a photo was taken, is removed from the result. Only the rotation needed to show the image the right way up is kept.

Questions & answers

Compress PNG: frequently asked questions

Why does PNG compression need a server?

Because browsers cannot do it. Canvas is the only way a browser can produce a PNG, and it ignores the quality argument for PNG — so a browser-based PNG compressor returns a file of the same size. Real compression needs palette quantisation, which runs on our server. Your upload is deleted immediately after processing and the result is deleted as you download it.

How much smaller will my PNG get?

Logos, icons, screenshots and flat illustrations commonly drop by 60–70%. Photographs saved as PNG barely improve, because they contain far too many distinct colours for quantisation to help — those should be converted to JPG or WebP instead.

Does compressing a PNG keep transparency?

Yes, including partial transparency. Quantisation reduces the colour palette while preserving the alpha channel, so a logo with a soft drop shadow keeps its shadow exactly.

Is PNG compression lossless?

PNG the format is lossless, but this tool is not: reducing the colour palette does discard information. That is the only way to make a PNG substantially smaller. At the default setting the change is usually invisible on graphics; on gradients you may see faint banding.

My file came back the same size. What happened?

It was already optimised, or it uses too few colours for quantisation to help. When the compressed result would be no smaller, we return your original rather than a larger file presented as a saving.

Should I compress the PNG or convert it to WebP?

If you must stay in PNG, compress here. If the image is for a website and you control the markup, WebP is usually better: smaller again and still transparent.

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