Why a target size beats guessing at settings
A video's file size is, roughly, its bitrate multiplied by its duration. Manually picking a bitrate to hit a size means doing that math yourself, then re-encoding if the guess is off. Target-size mode does that calculation for you: you supply the size, the app works out the bitrate.
The steps
Open the video in QuickCompress, switch to target-size mode, and type the exact size you need. Start the compression, and check the resulting file size once it finishes. The original file is left untouched throughout.
Why the same target does not behave the same on every video
Reaching a given target is not guaranteed to look the same, or even be reachable, on every source file. A short, low-motion clip has far more bitrate to spare at a given target than a long, high-motion, high-resolution one. Duration, resolution, motion, and how much of the target budget audio needs all affect the outcome for a specific file.
Picking which size to start from
If you do not already have a required limit, QuickCompress provides 10 MB, 25 MB, 50 MB, and 100 MB target options, plus a custom target. The target-size pages explain how to approach each preset.
Frequently asked questions
Will a chosen target size always be reachable without visible quality loss?
No. Whether a target is reachable, and how it looks if it is, depends on the source: its duration, resolution, motion, and audio all affect the outcome. A target that works cleanly on one video is not a guarantee for a different one.