Image Resizing: Width, Percentage, and Longest-Edge Scaling
Resizing looks like a single number change, but width, percentage, and longest-edge modes produce different results. Pick the wrong one and a batch will come out with mismatched dimensions.
When you need to resize an image
Dimension requirements are the most common reason. Application portals cap width, social platforms cap the longest edge, and marketplaces want a consistent width for listing images. Uploading the original may be rejected or recompressed badly by the platform; exporting at the right size gives you more control over the result.
Consistency is the second reason. Covers, product grids, and slide images look messy when their widths differ. Scaling a set to a shared width and then arranging the heights is more reliable than adjusting each file by hand. When the only goal is a smaller file, resizing often helps more than quality reduction alone.
Choosing between the three modes
Width mode suits a hard horizontal requirement; height is calculated from the original ratio, so images in the same batch may end up with different heights. Percentage mode scales width and height by the same factor, which is useful for halving a whole set. Longest-edge mode enforces a ceiling on the longer side, so both landscape and portrait images are constrained.
Most resizers lock the aspect ratio, which is what you want: faces and products should not be stretched. If you need an exact fixed size, crop to the target ratio first, then resize. Turning a 4:3 image into 16:9 without losing content requires padding, not stretching. Treat presets as a starting point and confirm the pixel dimensions before exporting.
- Hard width requirement: use width mode
- Scale a whole set: use percentage
- Cap the longer side: use longest edge, which normally only shrinks
Alternatives, and when not to resize
Upscaling does not add detail. Canvas interpolates between existing pixels, so a small image stretched to a much larger size only looks softer. If you genuinely need more resolution, find the original high-resolution file or use a dedicated super-resolution tool; mild enlargement is usually acceptable, but large jumps are not.
On the web, a different display size does not always require a different file. CSS can control layout size, and srcset lets the browser choose an appropriate source for the screen. Real pixel changes matter for upload limits, print, and offline delivery. Keep the original and save the resized version separately.
FAQ
What is the difference between width, percentage, and longest edge?
Width fixes the width and derives the height from the ratio. Percentage multiplies both dimensions by the same factor. Longest edge caps the longer side and normally only shrinks, never enlarges. In a batch, the first two produce varying dimensions; longest edge only constrains the outer bounds.
Why does an enlarged image look blurry?
Scaling interpolates existing pixels; it cannot invent detail that was never captured. The larger the jump, the softer the edges and textures. Mild enlargement is often fine, but a big increase calls for AI super-resolution or a genuinely higher-resolution source.
Why are my batch-resized images different sizes?
That is expected. Width mode keeps the width constant while each height follows its own ratio, and percentage mode scales each image from its own dimensions. For identical output, crop everything to the same aspect ratio first, then export at a fixed width and height.
Related tool：Resize Image