1. Match the pixel dimensions to the display area
Resizing an 800 × 600 GIF to 400 × 300 leaves one quarter of the pixel area. Actual encoded bytes depend on the scene and compression settings. Check small text at the intended display size, and keep the aspect ratio unless you deliberately want to change the shape.
2. Compare palette size and dithering
Start by comparing 256, 128 and 64 colors. Skin, skies and shadows can show visible bands with fewer colors. Dithering distributes color errors to neighboring pixels, but can create grain or increase the file size. Compare the same scene with one setting changed at a time.
3. Check frame count and animation duration separately
Keeping fewer frames can make motion less smooth. The current tool adds skipped-frame delays to retained frames. Speed, trimming and delay rounding can also affect the final duration. Check fast motion and short captions rather than assuming that an unchanged total duration means unchanged animation quality.
4. Open the downloaded result
The preview displays encoded output. Compare actual bytes, dimensions, frame count and duration, then open the downloaded GIF. Re-encoding a file that is already optimized can produce a larger result. Keep the original and choose the version that meets the real upload and quality requirements.
5. A measured, reproducible sample
The original site-generated sample is 211,713 bytes, 360 pixels wide, with 18 frames and a recorded duration of 1,260 ms. The separate resized result is 75,263 bytes and 180 pixels wide, with 18 frames and the same recorded duration. This is one synthetic example, not a universal reduction rate. A frame-skipped test recorded nine frames and the same duration; do not attribute the resizing byte result to frame skipping.