How to Resize an Image

What resizing actually does

Resizing changes the number of pixels in an image. Making an image smaller removes pixels; making it larger adds new pixels through interpolation (the software guesses what the new pixels should look like based on neighboring ones).

This has a direct effect on file size: fewer pixels means less data, which means a smaller file.

Aspect ratio: the thing people forget

Aspect ratio is the proportional relationship between width and height. A 1200×800 image has a 3:2 aspect ratio. If you change the width to 600 but leave the height at 800, the image looks stretched or squished — the aspect ratio was broken.

Most resizing tools offer an aspect ratio lock. When enabled, changing the width automatically adjusts the height to maintain the original proportions. Keep this on unless you have a specific reason to distort the image.

When resizing helps

• Meeting specific requirements: A form that requires images at exactly 800×600 pixels, or a marketplace listing with minimum dimension rules.
• Reducing file size for web: A 6000×4000 photo from a camera is overkill for a website. Resizing to 1200×800 looks identical on screen and loads much faster.
• Creating thumbnails: Small versions of images for previews and galleries.

When resizing hurts

• Enlarging beyond original size: Making a small image larger doesn't add real detail — the software invents pixels, which results in a soft, blurry appearance.
• Repeated resizing: Each resize discards or interpolates data. Resizing an image multiple times degrades it more than resizing once from the original.

Resolution vs. dimensions

These are related but different. Dimensions are the pixel count (1920×1080). Resolution usually refers to pixel density — how many pixels per inch (ppi) when printed. For screen use, only dimensions matter. For print, both matter: a 1200×1600 image at 300 ppi prints at 4×5.3 inches.

Step-by-step: resizing an image

1. Upload your image and note its current dimensions.
2. Enter the target width or height — with aspect ratio locked, the other dimension adjusts automatically.
3. Download the result — check that it looks correct at the size you'll be using it.