Image Resizer

Fit, fill or stretch

Whenever your target dimensions have a different aspect ratio from the source, something has to give, and the three options here represent the three possible answers.

Fit inside scales the image until it fits entirely within the target box, leaving empty space on two sides. Nothing is cropped and nothing is distorted, but the result may not fill the frame. This is the safe default when the whole image matters.

Fill and crop scales until the box is completely covered and trims the overflow from the edges, centred. Nothing is distorted and the frame is full, but content at the edges is lost. This is what you want for a square social post from a landscape photo — as long as the subject is near the middle.

Stretch forces the image to the exact dimensions regardless of proportion. It is almost always wrong: faces become wide or narrow and circles become ovals. It exists for the rare case where the source is a texture or gradient with no recognisable geometry.

Enlarging does not add detail

Making an image smaller discards information, which is straightforward. Making it larger cannot invent information that was never captured — the extra pixels are interpolated from their neighbours, which produces a softer, blurrier picture rather than a more detailed one.

A 400-pixel-wide image scaled to 1600 will look noticeably soft. It will not look like a 1600-pixel photograph, because the detail simply is not there. If you need a larger image, go back to the original source before any downscaling happened.

The one honest use of upscaling is meeting a minimum-dimension requirement imposed by a system that will display the image smaller anyway. Beyond that, downscale rather than up wherever you have the choice.

Sizes worth knowing

1200 × 630 is the social preview card size used by Open Graph, which is what Facebook, LinkedIn and most link-unfurling systems read. Getting this right is the difference between a link that looks deliberate and one that looks broken.

1080 × 1080 is the Instagram square; 1080 × 1350 is the portrait format that occupies more screen space in the feed. 1920 × 1080 is Full HD, the right size for a slide background or a desktop wallpaper.

For web images, aim to serve roughly twice the display width to look sharp on high-density screens, and no more. An image displayed 600 pixels wide should be around 1200 pixels; anything beyond that is bytes your visitors download and never see.

Quality of the resize itself

This tool uses the browser's high-quality image smoothing for the resample, which handles downscaling well in a single step. Large reductions — say 4000 pixels down to 400 — occasionally look crisper if done in two stages, because a single very large step can lose fine texture.

The output format follows the input: JPEG sources stay JPEG, everything else is written as PNG to avoid introducing lossy compression where there was none. If you also want to change format or compress aggressively, run the result through the image converter or compressor afterwards.