Give it a size limit and it solves the bitrate, encodes in any of 20 formats (MP4 with your browser's own H.264 encoder, the rest with FFmpeg in WebAssembly) and re-encodes if the result comes out over. Or pick a quality. Every result is measured against the source before you download it.
A video's size is just bitrate × length. Everything here is a way of choosing that bitrate, or of spending it on fewer pixels.
A talking head needs a fraction of the bitrate a drone shot over trees does. So instead of guessing, this measures your footage.
The seven rows above fill in with real sizes and PSNR once measured; the sweet spot is the smallest row within 1.5 dB of the best.PSNR compares pixels exactly; it is not a model of human vision, but it moves the same way and is honest about what was measured. Click a row to compress at that bits-per-pixel.
Every one opens here and can be saved back as itself. Your browser reads what it can play; FFmpeg in WebAssembly reads and writes the rest. Pick a row to make it the output.