Resize Image for X (Twitter) Header

Shrinking an image (downscaling) generally preserves quality well since you are discarding detail the output does not need. Enlarging an image (upscaling) can soften or blur it, since the tool has to invent pixels that were not in the original — there is a limit to how much any resizer can improve on that.

"Exact pixels" sets a specific width and/or height (with an option to lock the aspect ratio). "Percentage" scales the whole image uniformly up or down. "Fit within" scales the image down or up so it fits inside a maximum width and height while keeping its original proportions.

The height is automatically calculated to keep the same proportions as your original image, so nothing gets stretched or squashed.

Yes, all three formats are supported as both input and output — the resize happens on the decoded image data, so transparency in PNG and WebP is preserved.

You can drop in multiple files and resize them all with the same settings in one batch, then download them individually or as a single ZIP.

No. Resizing happens entirely in your browser using the Canvas API — your images never leave your device.