Overview
Introduction
This tool resizes a JPG to an exact target width and height entirely in your browser, with no upload to any server.
An optional aspect-ratio lock makes it easy to scale proportionally without doing the math yourself.
What Is JPG Resizer?
A client-side JPG resizing tool that decodes an uploaded image onto a canvas, resamples its pixel data to new dimensions using nearest-neighbor interpolation, and re-encodes the result as a JPEG.
It supports both stretching to an arbitrary width/height pair and locked-aspect scaling from a single dimension.
How JPG Resizer Works
For every pixel in the target-size output, the tool maps back to the nearest corresponding pixel in the source image and copies its color, which is the same strategy the shared pixel-buffer helper uses across every image tool on this site.
When the aspect-ratio lock is on, changing one dimension recomputes the other from the source image's original width-to-height ratio before the resize runs.
When To Use JPG Resizer
Use it to shrink a large camera photo down for faster web loading, scale a product image up to fill a fixed layout slot, or standardize a batch of images to the same dimensions one at a time.
It's also useful any time you need precise pixel dimensions rather than a proportional scale factor (for that, see the upsizer/downsizer tools).
Often used alongside PNG Resizer, JPG Upsizer and JPG Downsizer.
Features
Advantages
- Runs entirely client-side; the uploaded photo is never sent to a server.
- Supports exact target dimensions, not just a scale percentage.
- Optional aspect-ratio lock prevents accidental stretching.
Limitations
- Nearest-neighbor resampling can look blocky on large size increases compared to a smoothing algorithm.
- Both dimensions are capped at 4096 pixels per side.
Examples
Best Practices & Notes
Best Practices
- Keep the aspect-ratio lock on unless you specifically want to stretch or squash the image.
- For a proportional scale rather than an exact target size, the upsizer/downsizer tools are a more direct fit.
Developer Notes
resizeJpg is a thin validating wrapper around the shared resizeNearest helper from the jpg pixel-buffer module (nearest-neighbor resampling, not bilinear); the choice keeps hard edges crisp and matches the equivalent PNG-category resizer's behavior for consistency across the site.
JPG Resizer Use Cases
- Shrinking a camera photo for faster web page loads
- Scaling a product photo to a fixed layout slot's exact dimensions
- Standardizing a batch of images to one resolution
Common Mistakes
- Turning off the aspect-ratio lock and not noticing the picture is now stretched.
- Requesting dimensions above the 4096px maximum and getting an error instead of a truncated result.
Tips
- If you only know a percentage scale (like '50% smaller'), the downsizer tool is more direct than computing exact pixel dimensions here.
- Combine with the cropper first if you need a specific crop before resizing to a final size.