MP4 File Size Calculator

The MP4 File Size Calculator estimates the output MP4 file size from duration, video bitrate, and audio bitrate, with optional overhead and container assumptions. It outputs approximate sizes in MB and GB and supports common input formats. This tool is intended for video editors, producers, educators, and asset managers who need quick storage, bandwidth, and budget planning.
Conceptually, the size is derived from the sum of the video and audio bitrates multiplied by the duration, divided by eight to convert bits to bytes, with an optional overhead factor to account for container metadata. It accepts bitrates in Mbps and kbps and exposes outputs in MiB and GiB using binary units. For variable bitrate (VBR) scenarios, users can provide an average bitrate to obtain a reasonable estimate.
This tool enables rapid checks during pre‑production and post‑production workflows without encoding, making it useful for planning, budgeting, and asset management. It supports both single and multiple audio tracks by aggregating their bitrates, or by providing an average, to reflect target encoding scenarios.
Core features include input validation, clear unit reporting, and two-decimal formatting for MB/GB outputs. The approach prioritizes transparency in calculations and quick scenario testing, helping teams compare targets and confirm storage and bandwidth requirements before encoding.