Frame rate is how many images per second the video contains. 24 and 30 fps are standard; 60 fps is common for gameplay and sports; phones shoot 240 fps for slow motion.
The arithmetic invites a mistake. Halving 60 fps to 30 halves the number of frames, so it looks like a 50% saving. It is not, for two reasons. First, consecutive frames are highly similar, and codecs store the difference between frames rather than each frame in full — so the second of a pair of near- identical frames was already cheap. Second, spending the recovered bits is not free: at a fixed bitrate, fewer frames means more data per frame, which is a real quality gain, but it is a gain in still detail traded against smoothness.
In practice:
- Camera and screen footage at 60 fps can usually go to 30 with a modest size reduction and a visible change in how motion reads. Whether that is acceptable depends entirely on the content.
- Gameplay and sports are where 60 fps earns its keep. Halving it is the most noticeable degradation available.
- YouTube's own guidance is to upload at the source frame rate, and its recommended bitrates are higher for high-frame-rate uploads rather than the frame rate being treated as a compression knob.
Resolution and duration are almost always the better levers. Reach for frame rate last, and only when the footage does not depend on motion.