UnderKb

Resize

Resize an image

Enter width, height, or both. Fit keeps aspect; fill crops; stretch distorts.

Cambia el ancho y el alto. Encajar, recortar o estirar. JPG, WebP o PNG.

How to use it

  1. Drop the image

    Same 20 MB limit as the rest of UnderKb.

  2. Width and height

    One value keeps aspect. Both together use the mode you pick.

  3. Download

    JPG for photos, PNG for transparency, WebP for a smaller file.

What resize actually changes

  • One side keeps aspect

    Set only width or only height and we compute the other. No stretch unless you pick stretch.

  • Fit vs fill

    Fit letterboxes. Fill crops. Stretch distorts. The labels match what you get.

  • Then pick a format

    JPG for photos, PNG for alpha, WebP if you also want it smaller.

  • Server cap

    The long edge on the server is 4096 px. Huge camera files are scaled in the browser first.

Typical resize jobs

  • Avatar 256

    Set width 256, leave height empty, Fit.

  • Crop to a banner

    Set both sides and Fill so the subject stays in frame.

  • Email inline

    Resize first, then compress to KB if the host still rejects the file.

Limits

Long edge 4096 px on the server. Stretch will look ugly — that is the mode doing what you asked. We do not upscale a 32 px icon into a sharp poster.

FAQ

Can I set only the width?

Yes. Height is computed so it is not stretched. Same the other way.

Is there a maximum?

The long edge on the server is 4096 px. Huge camera files are scaled in the browser first.

Fit, fill, or stretch?

Fit keeps the whole image. Fill crops to the box. Stretch distorts.

Can I compress after?

Yes — open Compress to KB with the resized file if a host still rejects the size.

Do you store the file?

About 30 minutes in memory, then it expires.

Other tools