Image Resizer

The four fit modes

Cover scales the image until it fills the whole box and crops whatever hangs over the edges, which is what thumbnails and hero crops usually want. Contain scales it down until the entire image fits and leaves the remaining space empty, so nothing is cut off. Fill stretches the image to the exact box and ignores the original aspect ratio. Inside scales the image to fit the box but keeps the resulting size, so the output is never padded.

Dimensions and output

With the lock on, changing the width updates the height from the source aspect ratio and vice versa. Unlock it to enter both independently. The output format decides how the result is encoded: PNG is lossless and keeps transparency, WebP and JPG trade fidelity for size through the quality slider.

Resizing happens on a canvas in the page, so the image is never uploaded and the tool keeps working offline. Letterboxed areas stay transparent, which JPG — having no alpha channel — renders as black.