Overview
Introduction
Resizing an animated GIF to an exact pixel size, for embedding in a specific layout, meeting a platform's size limits, or just matching another asset, means resampling every frame consistently.
This tool decodes each frame, resizes it to your target dimensions, and re-encodes a new animated GIF, entirely in your browser.
What Is GIF Resizer?
A client-side tool that resamples every frame of an animated GIF to an exact target width and height using nearest-neighbor interpolation, with an optional aspect-ratio lock that derives the height automatically from the width and the source's own proportions.
It builds on this category's shared resizing helper, the same one gif-enlarger, gif-shrinker, and gif-upscaler use.
How GIF Resizer Works
For each output pixel, the tool maps back to the nearest corresponding source pixel using simple width/height ratios, copying that pixel's exact color rather than blending neighboring pixels.
This runs once per decoded frame at the same target dimensions, so every re-encoded frame ends up the same size, satisfying the shared GIF encoder's one-canvas-size-per-file requirement.
When To Use GIF Resizer
Use it when you need an animated GIF at an exact pixel size, like a specific banner or thumbnail dimension.
Turn on aspect-ratio lock when you only care about one dimension (usually width) and want the other computed automatically to avoid stretching.
Often used alongside GIF Enlarger, GIF Shrinker and GIF Rectangle Fitter.
Features
Advantages
- Gives exact, predictable output dimensions rather than a relative percentage scale.
- Optional aspect-ratio lock prevents accidental stretching when you only mean to change one dimension.
- Runs entirely client-side; nothing you upload leaves your browser.
Limitations
- Nearest-neighbor resampling can look blocky on large size increases and can lose fine detail on large decreases; for smoother large decreases, gif-downscaler's area-averaging may look better.
- Without aspect-ratio lock, mismatched width/height inputs will visibly stretch or squash the animation.
Examples
Best Practices & Notes
Best Practices
- Turn on aspect-ratio lock unless you specifically want to stretch or squash the animation to fit a fixed non-proportional box.
- For large reductions in size, compare the result against gif-downscaler's area-averaged output to see which looks better for your source content.
- Resize before cropping if you want a specific final pixel size with room to trim afterward.
Developer Notes
resizeGif in gif-resizer.ts wraps the shared resizeNearest helper (from png/lib/shared/pixel-buffer.ts) applied per decoded GIF frame via transformGifFrames, mirroring png-resizer.ts's own thin-wrapper structure. The aspect-ratio-lock branch recomputes height from the per-frame context's source width/height ratio rather than a value the caller supplies, so it can't drift from the actual source proportions.
GIF Resizer Use Cases
- Resizing an animated GIF to fit a specific banner, thumbnail, or embed size
- Matching an animated GIF's dimensions to another fixed-size asset in a layout
- Producing a smaller or larger exact-dimension variant for a size-constrained platform
Common Mistakes
- Entering mismatched width/height values without aspect-ratio lock and getting an unintentionally stretched or squashed result.
- Expecting nearest-neighbor resizing to look as smooth as a photo-editing tool's bicubic resize; it deliberately keeps hard edges rather than blurring them.
Tips
- If you only know the width you need, aspect-ratio lock saves you from calculating the matching height by hand.
- For a contain-fit into a box with letterboxing instead of exact-dimension resizing, use gif-rectangle-fitter.