Resize a PNG Image
Resizing a PNG here is a lossless round trip: the pixels are resampled to your dimensions and written straight back out with PNG's lossless compression, alpha channel included. There is no quality decision to make — the slider in the settings panel only applies to lossy formats and is ignored when the output is PNG. What deserves your attention instead is how PNG file sizes behave after a resize, and what smooth resampling does to hard-edged images. Both have surprises.
Why there is no quality choice for PNG
PNG has a single compression scheme and it is lossless, so the encoder has no quality dial to expose: the pixels that come out of the resample are stored exactly, every time. That is why the tool ignores the slider for this format — the engine never passes a quality value to a PNG encode.
The only information you lose is what the resampling itself removes. Going from 2000 pixels wide to 1000 discards three quarters of the samples, and no encoder choice was involved in that. It also means repeated resizes do not stack up damage the way lossy formats accumulate it: ten saves cost the same as one, provided the dimensions stop changing. If you need a smaller file at the same dimensions, that is a compression problem rather than a resizing one.
The output is always full 32-bit — palette files grow
Many PNGs on the web are palette files: instead of storing a colour per pixel, they store an index into a table of at most 256 colours, which makes icons and simple graphics tiny. The browser decodes any such file to full RGBA, and this tool writes the result back as a full 32-bit image, because the canvas it draws on has no notion of a palette.
The consequence is counter-intuitive: a carefully optimised 30 KB palette icon can come back larger after being made smaller, since the palette trick is gone from the output. Upscaling compounds it — lossless compression has to account for every new pixel, so doubling the dimensions of a PNG roughly quadruples the raw data it must store. When an optimised file matters, keep the original and treat the resized copy as derived output.
Hard edges, pixel art and smooth interpolation
The resampler is the browser's high-quality smoothing filter, and there is deliberately no nearest-neighbour option. For photographs that is the right filter. For pixel art, one-pixel grid lines and small UI text it is the wrong one: smoothing splits crisp single-pixel edges across neighbouring pixels, and they come out grey and soft. Photographs, by contrast, have no hard edges to protect and can be scaled freely.
Three ways to limit the damage. Scale by clean whole factors — 50% turns two pixels into one instead of one and a half. Crop away what you do not need instead of shrinking everything, which keeps the surviving pixels untouched. And never enlarge pixel art here; interpolation is exactly what its style forbids, and a dedicated editor with nearest-neighbour scaling is the right instrument for it.
Frequently Asked Questions
Is the transparent background kept?
Yes, in full. The alpha channel is resampled together with the colour channels, so partial transparency — soft shadows, anti-aliased edges — survives at the new size. It only disappears if you later convert the file to a format that has no alpha.
I shrank my PNG and the file got bigger. How?
Your original was almost certainly a palette file. The output is written as full 32-bit RGBA, so the space saved by fewer pixels can be outweighed by the loss of the palette encoding. Keep the original when it was hand-optimised.
Can this resize an animated PNG?
Only its first frame — an APNG comes out as a motionless image, and no warning appears for this format. Check the result before replacing anything you care about.
My PNG is actually a photograph. Should it stay PNG?
Probably not. Lossless compression stores continuous-tone detail expensively, so a photographic PNG stays heavy at any dimensions. Resize it here, then let the image converter turn it into WebP or JPEG; the drop in file size is usually dramatic.
What if my image's shape doesn't match the width and height I typed?
Pick a fit mode. Fill & Crop trims the image to fill your exact box; Stretch distorts it to fit; Fit Inside keeps everything, but the output shrinks to the image's fitted size — smaller than the box you typed, never padded to it.
Is the embedded colour profile preserved?
No. The image is rebuilt in the browser's standard sRGB space and any embedded profile is left behind. Irrelevant for screenshots and web graphics; for colour-managed print work, resize in an application that keeps profiles.