GIF Speed Changer

A GIF plays each frame for a delay stored in the file, in hundredths of a second. This tool rewrites those delays to make a GIF faster or slower, gives every frame the same time, or stretches the whole animation to a length you choose — and it changes nothing else: the frames, colours and transparency stay byte for byte as they were, so there is no quality loss and the file size stays the same. You can also change how many times the GIF loops. Everything runs in your browser.

How to use this tool

1. Choose one or more GIFs.
2. Pick a speed such as 2× or 0.5×, a fixed time per frame, or a total length.
3. Optionally change the looping (forever, once or a number of plays).
4. Download the new GIF.

Formula

new delay = original delay ÷ speed (rounded to 1/100 s, keeping the total exact)

Delays are rounded so that the start time of every frame stays as close as possible to the exact one, so the total length is right even when single delays round up or down. Browsers play delays of 0 or 1 hundredth of a second as 1/10 s, so those are counted as 1/10 s. If speeding up would push frames under 2/100 s — the fastest browsers show — frames closer together than that are dropped (the picture is rebuilt from the frames that remain) and the length is still exact.

Example

A GIF of 12 frames at 80 ms lasts 12 × 0.08 = 0.96 s. At 2× each delay becomes 40 ms and the loop lasts 0.48 s. At 4× the delays would be 20 ms — still allowed — giving 0.24 s; at 6× they would fall under 20 ms, so every second frame is dropped and the remaining six frames last 40 ms each.