GOP Length Calculator

A GOP — group of pictures — is the run of frames that starts at a keyframe, so the keyframe interval and the GOP length describe the same setting from two sides. Encoders usually take the length in whole frames: interval × frame rate, so a 2 s interval at 25 fps is a GOP of 50 frames and at 29.97 fps it is 60 frames (59.94 rounded up), which is 2.002 s. The keyframe count is the number of GOPs that start in the clip, one per interval plus the opening frame, rounded up. The table below lists 0.5, 1, 2, 4 and 10 s intervals at the entered rate, where the effective column is the rounded GOP divided by the frame rate and the keyframe counts cover the clip above. Frame rates are limited to 1–240 fps, intervals to 0.1–60 s, GOP lengths to 1–20,000 frames and clip durations to 1–86,400 s; a GOP never drops below one frame. Some encoders clamp the GOP or force extra keyframes at scene cuts, so treat the result as the arithmetic value rather than a promise of the encoder's output. Everything runs locally in your browser with no storage, uploads or network access.