Compress PNG
Process images in your browser — your files never leave your device.
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What is the Compress PNG?
This tool compresses PNG files by re-encoding them losslessly with DEFLATE — the same compression PNG has always used — and, more usefully, by letting you cap the pixel dimensions before it re-encodes. PNG is a lossless format: it stores every pixel exactly, so there is no quality slider that can trade fidelity for size the way JPEG has. Re-encoding alone typically saves only a small amount unless the original file was poorly optimized. If you need a PNG meaningfully smaller, the max-dimension and target-size controls do the real work here by shrinking the pixel grid, not by degrading colour.
If your PNG doesn't need transparency, converting it to JPEG or WebP first — with the Image Compressor or PNG to JPG — will almost always beat what this tool can do on file size, because both of those formats can discard data PNG is not allowed to. Keep using PNG compression when transparency, exact colour or lossless quality actually matters: logos, icons, screenshots with text, and diagrams.
Why use a free compress png?
Genuinely lossless
Every pixel in the output matches the input exactly, down to alpha transparency. Nothing here can introduce blocking, banding or colour shift the way lossy re-encoding can.
Honest about its limits
PNG re-encoding rarely produces dramatic size reductions on its own — this tool tells you that up front instead of pretending a quality slider does something it cannot.
Max dimension does the heavy lifting
Capping the longest side before re-encoding cuts file size proportionally to the pixel count removed — a PNG resized from 3000px to 1200px wide typically ends up 4–6× smaller.
Transparency preserved exactly
Alpha channels, including partial transparency and hard edges around logos or icons, come through unchanged.
Batch processing, nothing uploaded
Compress a whole folder of screenshots or icons at once and download them as a ZIP, all processed locally in your browser.
How do you use the Compress PNG?
- 1
Add your PNG files
Drag and drop one or more .png files. Files keep their transparency in the preview thumbnail.
- 2
Read the built-in note about PNG compression
The tool explains upfront that re-encoding alone rarely shrinks a PNG much, and points you to the dimension control for real savings.
- 3
Set a max dimension if the PNG is larger than it needs to be
This is where most of the file size reduction actually comes from — capping the longest side to your real display size.
- 4
Compress and compare
Click Compress and check the before/after size on each file. A screenshot with lots of flat colour will shrink more than a PNG holding a dithered photo.
- 5
Download
Download files individually or as a ZIP once more than one is finished.
How is compress png calculated?
Reduction % = (original size − compressed size) ÷ original size × 100Where:
- original size
- Size of the source PNG in bytes
- compressed size
- Size after re-encoding, with any dimension cap applied
- pixel count
- Width × height — the single biggest lever on PNG file size, since compression itself is lossless and fixed
The simple version
PNG compresses each row of pixels with a lossless algorithm (DEFLATE, the same one ZIP uses) after a filtering step that makes adjacent pixels more predictable. There's no dial that discards detail for a smaller file — the only two things that meaningfully shrink a PNG are fewer pixels (resize it) or fewer distinct colours (which this tool does not force, since that would stop being lossless).
What does it look like in practice?
Screenshot, re-encoded at original size
Input
1.4 MB PNG screenshot, 2560×1440, no dimension cap
Result
~1.1 MB
A modest saving — most screenshot tools already compress reasonably well, so re-encoding alone rarely does much more.
Same screenshot, resized down
Input
Same 1.4 MB PNG, max dimension set to 1280px
Result
~340 KB
Cutting the longest side in half roughly quarters the pixel count, and file size drops in step with it — this is where the real reduction comes from for PNG.
Photo mistakenly saved as PNG
Input
8.6 MB PNG of a photograph, 4000×3000, no dimension cap
Result
~7.9 MB
Photographic detail defeats lossless compression almost entirely — this is the case where converting to JPEG instead, not compressing as PNG, is the right move.
How accurate is it?
Re-encoding uses the browser's native lossless PNG encoder via Canvas, so pixel data is bit-for-bit unchanged unless you also set a max dimension. The size shown after compression is the exact size of the downloadable file.
- The quality slider shown in this tool has little to no effect on PNG output, because PNG has no lossy quality parameter — browsers ignore it for this format. Dimension and target size are what actually change the result.
- Savings from re-encoding alone depend on how the PNG was originally saved — files exported by some design tools carry redundant metadata or suboptimal filtering that a fresh encode trims; files already optimized by tools like pngcrush see little change.
- Photographic content compresses far worse than flat-colour graphics under PNG's lossless algorithm, regardless of settings — this is a property of the format, not a limitation of this tool.
What should you know before using it?
PNG next to JPEG and WebP for compression behaviour:
| Format | Compression mechanism |
|---|---|
| PNG | Lossless DEFLATE. No adjustable quality. Full alpha transparency. Best for screenshots, logos, icons and diagrams. |
| JPEG | Lossy DCT with adjustable quality — see Compress JPEG. No transparency, but far smaller for photographic content. |
| WebP | Supports both lossy and lossless modes with transparency — often the better lossless choice for a PNG that needs to be smaller. See Compress WebP. |
Which tools relate to the compress png?
The compress png is one of 31 image tools on this site. These are the ones most often used alongside it — either because they handle the next step in the same job, or because they answer a question this tool raises.
Compress WebP
WebP's lossless mode typically beats PNG on file size for the same pixel-exact output, while keeping full alpha transparency.
Image Resizer
Since dimension is what actually shrinks a PNG, resizing before or instead of compressing here is often the more direct route to a smaller file.
PNG to JPG
If the image does not need transparency, converting to JPEG first gets a far smaller file than any amount of PNG re-encoding can.
Compress JPEG
For photographic content saved as PNG by mistake, converting and compressing as JPEG produces a dramatically smaller result than staying lossless.
When should you use a compress png?
Because the compress png runs entirely in your browser, it suits work you would not want to hand to a third-party server — client files, unpublished drafts, anything under an NDA. These are the situations people reach for it in most often.
Screenshots for documentation
Screenshots with text and UI elements need PNG's lossless, sharp-edge rendering — this tool trims their size without touching that sharpness.
Logos and icon sets
Brand assets need exact colour and clean transparency edges. Compressing here keeps both while cutting excess file weight from export bloat.
Favicon and app icon preparation
Icon source files are often exported oversized. Cap the dimension here, or use the Favicon Generator directly for multi-size icon output.
Open the Favicon and app icon preparationDesign handoff and asset libraries
Shrinking a batch of PNG assets before adding them to a shared library or CMS keeps storage and page weight down without changing how anything looks.
Frequently asked questions
Can you compress a PNG without losing quality?
Why is my PNG still large after compressing it?
Does the quality slider do anything for PNG?
Will compressing a PNG remove transparency?
Should I use PNG or JPEG for a screenshot?
Is a photo saved as PNG better quality than JPEG?
Is the compress png safe to use?
This tool runs entirely inside your browser. Your text, files and settings are processed on your own device and are never uploaded to our servers — there is nothing for us to store, log or leak. You can confirm it yourself: open your browser DevTools, switch to the Network tab, and use the tool. You will not see an upload request. It also means the tool keeps working if your connection drops mid-task.
Where do these figures come from?
Every method, threshold and standard this page relies on, with a link to the document that defines it. Check them — a tool that will not show its sources is asking you to take its word for it.
- 1Portable Network Graphics (PNG) Specification (Third Edition)
W3C · 2003
Supports: The lossless DEFLATE compression, per-row filtering step, and full alpha-channel support described as PNG's compression mechanism.
- 2Image file type and format guide
MDN Web Docs
Supports: The comparison table showing PNG as lossless with no adjustable quality parameter, versus JPEG and WebP.
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