Preserve the width-to-height relationship
A 1600 × 900 image has a 16:9 ratio. Reducing its width to 800 while preserving proportions gives a height of 450.
Forcing 800 × 800 without preserving the ratio stretches it. To fill a square without distortion, crop the frame before or after resizing.
Reducing or enlarging
Reducing dimensions decreases the pixel count. Enlarging interpolates existing pixels; it cannot recreate details absent from the original.
Pixel dimensions and byte size are different measurements. Format, quality and image contents also affect file size.
- Load a supported image and check its dimensions.
- Enable aspect-ratio preservation to avoid distortion.
- Enter the target width or height.
- Download and compare sharpness, shape and dimensions.
Before publishing or printing
For a website, use dimensions appropriate to the actual display space. For printing, check physical size and the resolution required by the printing process.
Keep the original and check transparent edges, colors and metadata: browser re-export may alter them. Resizing happens locally.