Resize images online

How to resize an image

1. Drop one or more images onto the box above, or click it to browse. JPG, PNG, WebP, AVIF, GIF and BMP are all read directly by your browser.
2. Choose how the new size is worked out: by pixels for an exact width or height, by percentage to scale everything down proportionally, or a preset for a known screen or social size.
3. Leave the chain button locked to keep the original proportions. Each image is then scaled from whichever side you typed into, so a mixed batch of portrait and landscape photos stays undistorted.
4. Press Resize. Download the files one at a time, or grab the whole batch as a ZIP.

Why the resampling filter matters

Making an image smaller means throwing away pixels, and how you throw them away decides whether the result looks sharp or mushy. The naive approach — nearest-neighbour sampling — picks one source pixel per output pixel and discards the rest, which produces jagged edges and shimmering detail. This tool uses lanczos3, a windowed sinc filter that takes a weighted average of a 6 × 6 neighbourhood for every output pixel. It is the same resampler used by ImageMagick, Squoosh and most professional photo software, and it is noticeably crisper than the browser's built-in scaling on text, fine textures and diagonal lines.

Resampling happens in linear RGB with premultiplied alpha, which avoids the dark halos you sometimes see around the edges of transparent PNGs that were scaled naively in gamma space.

Upscaling: what is honestly possible

Enlarging cannot add detail that was never captured — the extra pixels are interpolated from their neighbours, so a 400 px image blown up to 1600 px will always look soft. Lanczos does this about as well as a classical filter can, but if you need a genuine increase in detail you need the original file at a higher resolution, or a machine-learning upscaler. That is why “don’t enlarge images that are already smaller than the target” is switched on by default: it stops a batch preset from silently blowing up your smallest files.

Common target sizes

Resize or compress?

They are different levers and they multiply. Resizing changes the pixel count: halving both dimensions removes three quarters of the pixels and usually three quarters of the bytes. Compression changes how many bits each remaining pixel costs. For a photo destined for a web page, resize first to the largest size it will ever be displayed at, then compress to around 80% quality. That combination routinely turns a 6 MB phone photo into a 120 KB file that still looks perfect on a retina screen.