How to Resize Images: Width, Height, Ratio, and Pixels Explained
Learn image resizing basics, including width, height, pixels, aspect ratio lock, scaling, and upload size requirements.
Updated: 2026-05-01Image ResizePixelsAspect Ratio
What resizing changes
Resizing changes the pixel width and height of an image. A 4000×3000 photo can be resized to 1200×900 for web use. This is different from compression, although resizing often reduces file size too.
When resizing helps
Use resizing for upload requirements, website images, avatars, covers, product images, and consistent design assets. Large original phone photos are often unnecessary for web display.
Keep aspect ratio
Aspect ratio lock prevents distortion. If you change the width, the height updates proportionally. Without this, people may look stretched and circles may become ovals.
Resize vs crop
Resizing keeps the full image and changes scale. Cropping removes parts of the image to fit a target ratio. For a fixed cover size, you may need to crop first, then resize.
Summary
Resize images according to where they will be used. Keep proportions, avoid unnecessary enlargement, and save the original file for future editing.