Video File Size Calculator
Enter how long a video runs and the bitrates of its video and audio streams to estimate the finished file size. Useful for planning exports, checking platform upload limits, or sizing a recording before you press record.
Result
- Estimated file size
- 609.6 MB
- In gigabytes
- 0.6096 GB
- In gibibytes
- 0.5677 GiB
- Combined bitrate
- 8.128 Mbps
Decimal megabytes (1 MB = 1,000,000 bytes).
1 GB = 1,000,000,000 bytes.
1 GiB = 1,073,741,824 bytes. Many operating systems label this "GB".
How it is calculated
A bitrate is data per second, so size is bitrate multiplied by time, divided by 8 to convert bits to bytes:
bytes = (video_bps + audio_bps) × seconds ÷ 8
Video bitrate in Mbps is multiplied by 1,000,000 and audio in kbps by 1,000 to get bits per second. Results are shown in decimal megabytes (MB, 106 bytes), decimal gigabytes (GB, 109bytes) and binary gibibytes (GiB, 230 bytes). The same file is about 7% smaller when expressed in GiB than in GB.
Worked example
A 10-minute clip at 8 Mbps video and 128 kbps audio has a combined bitrate of 8.128 Mbps. Over 600 seconds that is 8,128,000 × 600 ÷ 8 = 609,600,000 bytes: 609.6 MB, 0.6096 GB, or about 0.568 GiB.
Assumptions and limits
- Constant bitrate. Many encoders use variable bitrate (VBR), where the number you set is an average or a ceiling. Real files can land noticeably above or below the estimate, especially for static or very busy footage.
- Container overhead is not included. MP4, MOV and MKV containers add indexes, metadata and packet headers, typically a small fraction of a percent to a couple of percent. Real files can come out smaller or larger than the estimate, so treat it as an approximation, not a lower bound.
- Bitrate changes size linearly. Doubling the bitrate doubles the file; there is no saving from the calculator itself. Quality at a given bitrate depends on the codec and settings.
- Subtitles, extra audio tracks and embedded thumbnails are not counted.