A practical calculator for turning an upload limit into a video bitrate, with enough margin for audio and container overhead.
“Make this video smaller” is an open-ended request. “Make this three-minute video fit under 10 MB” is an engineering constraint.
The second version sounds more precise, but a quality slider alone cannot solve it. A quality setting tells an encoder how aggressively to preserve detail. It does not directly tell us how many bytes the final file may contain. If the destination has a hard upload limit, the useful starting point is a bit budget.
This article builds that calculation in TypeScript, then looks at the assumptions that make the answer less exact than the formula first appears.
File Size Is Bitrate Multiplied by Time
