PNG is lossless
PNG keeps every pixel exact, so re-saving alone won't shrink it much. The two levers that really help are below.
Reduce PNG file size while keeping crisp edges and transparency — ideal for screenshots, logos and graphics. For the biggest savings, convert to WebP in one click. All in your browser.
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PNG keeps every pixel exact, so re-saving alone won't shrink it much. The two levers that really help are below.
Set the output format to WebP to cut file size by 60–90% while keeping transparency — perfect for the web.
If the image is larger than it needs to be, resizing the dimensions is the fastest way to drop the size.
PNG never discards image data. Every pixel you put in comes back out identically, which is why it is the right format for screenshots, logos, diagrams and anything with text. Compression therefore cannot mean "throw away detail" — it means encoding the same pixels more efficiently.
Two mechanisms do the work. First, PNG applies a per-row filter that stores the difference between each pixel and a prediction from its neighbours, turning smooth gradients into long runs of small numbers. Choosing a good filter per row makes a substantial difference and is where optimisers spend most of their effort. Second, the filtered data is compressed with DEFLATE, the same algorithm as ZIP.
Because it is lossless, a PNG optimiser can only rearrange and re-encode. Typical savings on an unoptimised export are 10 to 30 percent — worthwhile, but nothing like the order-of-magnitude reductions lossy formats achieve on photographs.
The largest reductions come from reducing the palette rather than from better encoding. A true-colour PNG stores 24 bits per pixel plus 8 more for transparency. A palette PNG stores an index into a table of at most 256 colours, using 8 bits or fewer per pixel — an immediate reduction of two thirds or more.
For screenshots, icons, logos and flat illustration this is often visually lossless, because such images genuinely contain few distinct colours. A user-interface screenshot might use 200 colours in total, in which case a 256-colour palette reproduces it exactly.
The technique fails on photographs and smooth gradients, which contain thousands of subtly different tones. Quantising those to 256 colours produces visible banding, and dithering trades that banding for noise that both looks worse and compresses worse. For photographic content, PNG is the wrong format — use JPEG or WebP.
Exports from design tools routinely carry colour profiles, EXIF blocks, text chunks, generation timestamps and thumbnail previews. On a small icon this metadata can exceed the image data itself. Stripping it is free in visual terms, with one caveat: an embedded colour profile matters if the image relies on a wide-gamut space, and removing it will shift the colours.
It is also worth checking whether PNG is the right choice at all. If the image has no transparency and is photographic, JPEG will be dramatically smaller. If it does need transparency, WebP supports it with far better compression — commonly 25 to 50 percent below an optimised PNG — and is supported by every current browser.
PNG remains the correct answer for images that must be pixel-exact, for anything that will be edited repeatedly, and as a universally readable fallback. Just do not use it for photographs because it is "higher quality" — losslessly storing a photograph mostly stores its noise.
PNG is lossless, so simply re-encoding it has a limited effect. For real savings, switch the output format to WebP or resize the image — both keep transparency.
Yes. PNG and WebP both support transparent backgrounds. Only converting to JPG removes transparency (it flattens onto white).
For sharp UI screenshots and flat graphics, WebP usually gives the smallest file with no visible loss. Try it and compare the saving shown.
Yes — free, no account, and your images are compressed locally in your browser, never uploaded.
PNG is lossless, so an optimiser can only re-encode more efficiently — typically 10 to 30 percent. The big win is reducing colour depth to a palette, which works well for screenshots and logos but causes banding on photographs.
No. Photographs have thousands of subtle tones and no flat regions, so lossless encoding mostly preserves sensor noise at great expense. Use JPEG or WebP, which are often ten times smaller with no visible difference.