Video File Size Calculator
Estimate how much space an exported video will use. Enter its duration and stream bitrates to compare decimal and binary file-size units.
Estimate your export size
Why use our video file size calculator?
- Estimates file size from duration, video bitrate, and optional audio bitrate
- Shows decimal MB and GB beside binary MiB and GiB without mixing unit systems
- Accepts video bitrate in either Mbps or kbps
- Includes practical presets for previews, web video, detailed demos, and high-bitrate exports
- Separates the video, audio, and combined bitrate values used in the estimate
- Runs instantly and privately in your browser with no file upload
Frequently asked questions
How is estimated video file size calculated?
Add the video and audio bitrates, multiply that total by the duration in seconds, then convert bits to bytes. With bitrate measured in kilobits per second, the formula is bytes = total kbps × seconds × 1,000 ÷ 8.
Why does the calculator show both MB and MiB?
MB and GB are decimal units based on powers of 1,000, while MiB and GiB are binary units based on powers of 1,024. One MB is 1,000,000 bytes and one MiB is 1,048,576 bytes, so the same file has different numeric values in the two systems.
Will my exported file be exactly this size?
Usually not exactly. This is the mathematical size of the video and audio stream budgets. Containers add overhead, and variable-bitrate encoders distribute data according to the content, so a finished export can be somewhat larger or smaller.
Does audio make a meaningful difference to file size?
Yes, especially for long videos or low-bitrate video. Audio size grows linearly with duration just like video size. Turn off the audio reservation for silent exports, or enter the audio bitrate configured in your encoder.
Can I estimate a variable-bitrate export?
Yes, if you enter the expected average bitrate rather than the peak bitrate. A peak or maximum bitrate describes only the highest-rate sections and will usually overestimate the file if treated as the average for the entire duration.
What video bitrate should I enter?
Use the target or average video bitrate from your export settings. Resolution alone is not enough to determine it: codec, frame rate, visual complexity, and quality settings all affect how much bitrate an encoder needs.
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