PNG files are larger than JPEGs because they use lossless compression that preserves every pixel exactly as it was created.
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Maintain transparency
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PNG, which stands for Portable Network Graphics, is a lossless format by design. Its deflate compression algorithm reorganizes pixel data into a more compact binary representation without discarding any information. The same pixels go in and the same pixels come out, byte for byte identical when decoded. This distinguishes PNG fundamentally from JPEG, which discards high-frequency data permanently in exchange for much smaller files. PNG's lossless guarantee is the reason it remains the standard for screenshots, UI elements, logos, technical diagrams, and any image where pixel-perfect accuracy matters more than file size. However, lossless does not mean uncompressible further. Standard PNG files exported from image editors typically use the default compression level of six out of nine. Recompressing at level nine can reduce a PNG by five to fifteen percent with absolutely no pixel change, just a more efficient encoding of the same data. Tools like pngcrush, oxipng, and zopflipng find better deflate representations without altering the image content at all.
When people say they want to "compress PNG without losing quality," they sometimes mean something different from pure deflate optimization. They often mean reducing a full-color 32-bit or 24-bit PNG to an 8-bit indexed-color PNG, also known as PNG-8. This process, called palette quantization, reduces the number of distinct colors stored in the image from 16.7 million down to a curated palette of 256. For images that already use a limited color range such as logos, icons, UI components, and flat illustrations, the visible difference between 24-bit and 8-bit is negligible or zero because the source image never needed all those colors in the first place. For images with smooth color gradients such as photographs or renders with soft shadows, quantization introduces visible banding in the gradient regions. Tools like pngquant apply advanced dithering to minimize banding, achieving 60 to 80 percent file size reduction on logo-class images with no perceptible quality difference. This is exactly what TinyPNG does behind the scenes: it applies pngquant-style quantization rather than simple deflate recompression, which is why it achieves much larger reductions than tools that only optimize the deflate stream.
For photographs saved as PNG by mistake, which is a surprisingly common outcome from screenshot tools and certain phone camera settings, neither deflate recompression nor palette quantization is the right approach. A 3000x2000px photograph saved as PNG can weigh 8 to 18 megabytes. Applying deflate recompression at level nine reduces it to perhaps 7 to 16 megabytes, which is hardly worth the effort. Applying palette quantization produces a 1 to 3 megabyte file but with very visible color banding in sky regions, skin gradients, and any other smoothly varying area. The correct approach for a photo accidentally stored as PNG is conversion to JPEG: export at quality 83% and you get a 300 to 800 kilobyte file with no visible quality loss for typical screen viewing. PNG is simply the wrong format for photographs because its lossless guarantee preserves no meaningful quality advantage over JPEG at 83% or higher for photos viewed on screen.
A nuance worth understanding is when PNG genuinely is the right format for a photo. The two cases are images requiring transparency, where JPEG cannot store an alpha channel at all, and images destined for further editing or print where every pixel might matter at large reproduction sizes. For these cases, optimizing the PNG with deflate level nine and possibly stripping out ancillary chunks like gAMA, sRGB, and tEXt metadata can squeeze out a useful 10 to 20 percent reduction without touching the pixels. For everything else photographic, JPEG at 83% or WebP at 80% delivers files 80 to 90 percent smaller with no visible difference, and the right answer is conversion rather than PNG-internal optimization.
Step-by-step guide to compress png without losing quality:
Upload your PNG file
Open the Image Compressor and upload your PNG image by dragging it into the upload area or clicking the file picker. The tool reads the PNG, detects whether it contains an alpha channel, and prepares the compression options accordingly.
Choose your compression approach
For logos and graphics with transparency, use quality 90 to 100 for lossless-like results that preserve sharp edges. For photographs that were mistakenly saved as PNG, convert to JPG or WebP first for drastically smaller files with no visible quality penalty on screen.
Check transparency is preserved
If your PNG has a transparent background, verify the compressed PNG maintains the alpha channel after downloading. Open the file against a dark backdrop or in a tool like Preview to spot any halo or fringing that would indicate a problem with the transparency handling.
Download the compressed PNG
Save the optimized PNG file to your downloads folder. The output keeps the original dimensions and color profile, so it drops directly into your design system, CMS, or app bundle without requiring any further adjustment.
Compare against the original
Place the original and compressed PNGs side by side at 100% zoom. For lossless mode you should see zero difference. For palette-quantized mode you may notice subtle changes in gradient regions, which is exactly the tradeoff you accepted when choosing the smaller file.
Common situations where this approach makes a real difference:
Web designer
A designer creates UI icons as 24-bit PNG files at 64x64px, each averaging 8 to 12 kilobytes. After applying palette quantization to reduce to 8-bit indexed color, each icon drops to 2 to 4 kilobytes with no visible quality difference at web display size. A UI kit of 200 icons shrinks from 2 megabytes to 500 kilobytes total. That 1.5 megabyte saving is meaningful for a design system loaded on every page of a large application, because it directly improves time-to-interactive on slow connections and reduces the data cost for mobile users on metered plans.
App developer
An iOS developer bundles 80 PNG assets in an app. Original 32-bit PNGs exported from Sketch total 4.2 megabytes. After running all assets through PNG compression at quality 92, which preserves alpha channels, the bundle total drops to 1.8 megabytes. App Store download size decreases by 1.2 megabytes after Apple's thinning pipeline applies, which improves conversion rates on low-storage devices that would otherwise decline the install when warned about space. The visual difference between original and compressed assets is invisible at the rendered display sizes.
Blogger using screenshot images
A software tutorial blogger uses full-page browser screenshots as PNG files, each 2 to 4 megabytes at 1920x1080px. After converting these to JPEG at 82 percent quality using the Format Converter, each screenshot is 120 to 280 kilobytes. The blog post loading time drops from 22 seconds with eight PNG screenshots at 3MB each to 1.8 seconds with the JPEG equivalents. Text in the screenshots remains perfectly legible, and the only viewers who notice the difference are the ones who measured the speed improvement.
Game developer
A mobile game developer has sprite sheets as large PNG files with transparency that is critical for gameplay rendering. After compressing each sprite sheet at quality 95, preserving transparency and sharp pixel edges, file sizes drop 12 to 18 percent with no visible change to sprite edges or colors. The game's asset bundle reduces from 85 megabytes to 72 megabytes, fitting within app store size recommendations for over-the-air downloads on cellular and avoiding the dreaded "this download requires Wi-Fi" prompt that costs installs.
Get better results with these expert suggestions:
Convert PNG photos to JPEG for 80 to 90 percent size reduction
If your PNG contains a photograph rather than a logo, UI element, or image with transparency, converting to JPEG at 82 to 85 percent quality via the Format Converter drops the file size by 80 to 90 percent with no visible quality loss on screen. A 6 megabyte PNG photo becomes a 400 to 700 kilobyte JPEG. The only legitimate reason to keep a photograph as PNG is if it has a genuinely transparent background that you need to preserve, in which case WebP lossless is a better option than PNG anyway.
Keep PNG for transparency and UI elements
PNG is the correct format for logos with transparent backgrounds, UI icons, buttons, and screenshots containing text with sharp edges. JPEG compression creates visible ringing artifacts around high-contrast edges like icon outlines and small text characters, which looks especially bad on retina displays. For these content types, the larger PNG file is fully justified by the quality difference at the edges, and any attempt to substitute JPEG will produce visibly worse results.
Use WebP lossless as a PNG replacement with smaller files
WebP supports a true lossless compression mode that is 26 percent more efficient than PNG at identical visual quality, with zero pixel difference. For web use where all users have modern browsers including Chrome, Firefox, Safari 14 and later, and Edge, converting PNG logos and UI elements to lossless WebP reduces file sizes 20 to 30 percent without any quality loss at all. Use the Format Converter to create WebP versions of your PNG assets while keeping the originals as fallbacks for any legacy environments.
Check that alpha channel transparency survives compression
After compressing a PNG with transparency, download the file and open it on a white background and then on a dark background. This two-background check reveals any artifacts in the transparent areas, such as halos or fringing, that might be invisible on a matching background. FixTools preserves alpha channels through compression. Converting to JPEG strips transparency entirely because JPEGs cannot store alpha channel data. If your PNG must retain transparency, never convert to JPEG.
More use-case guides for the same tool:
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