Video File Size Estimator
Estimate how large an export will be from its bitrate and duration.
This is an estimate assuming a constant average bitrate. Variable-bitrate (VBR) encodes will vary with content complexity.
How GenMotion's free file size estimator works
Three steps, no account, and nothing to install.
- Step 1
Enter bitrate and duration
Give the video bitrate, the audio bitrate and how long the piece runs. Or work backwards from a size you have to hit.
- Step 2
Check against your target
See the estimate in MB or GB immediately, so you know whether an export will clear an upload limit.
- Step 3
Adjust before you render
Tune the bitrate until the size fits, instead of discovering the problem after a long export.
Who is GenMotion's free file size estimator for?
Video editors
Plan an export that lands under a platform's file-size cap before committing to a render.
Developers
Budget storage and bandwidth for video assets, or size uploads against a limit you enforce.
Marketers
Check an ad or landing-page video will meet a channel's spec without a round trip to the editor.
Frequently asked questions
File size equals total bitrate multiplied by duration. In bytes: (video Mbps × 1,000,000 + audio kbps × 1,000) × seconds ÷ 8. This tool does the conversion and shows the result in MB or GB.
As a rough guide, 8 Mbps suits 1080p, 16–20 Mbps suits 1440p, and 35–45 Mbps suits 4K. Higher bitrates preserve more detail but produce larger files.
This estimate assumes a constant average bitrate. Variable-bitrate (VBR) encodes allocate more data to complex scenes and less to simple ones, so the real size varies with content.
It uses decimal units (1 MB = 1,000,000 bytes), which matches how bitrates and storage are usually advertised.
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