# Video file size calculator: bitrate to file size and back

> Calculate a video's file size from its video and audio bitrate and length, or the video bitrate that fits a target file size. Includes YouTube's recommended bitrates.

URL: https://cutfac.com/tools/video-file-size-calculator  
Last updated: 2026-10-28  
Language: [한국어](https://cutfac.com/ko/tools/video-file-size-calculator)

Enter the length and bitrates to see the file size, or switch to enter a size limit and get the video bitrate that fits it.

Runs in your browser. Nothing is uploaded.

## How to use it

1. **Pick what to work out.** File size from bitrate, or the bitrate that fits a file size.
2. **Enter the length and bitrates.** Type them in, or tap one of YouTube's recommended video bitrates.
3. **Read the result.** It updates as you type. Use the bitrate in your export settings, or check the size against your limit.

## How bitrate becomes file size

File size is bitrate times length. Bitrates count bits a second, so divide by 8 for bytes: 8 Mbps of video is 1,000,000 bytes a second, about 57 MB a minute. The audio bitrate adds to it.

Most video is encoded at a variable bitrate, so the real file can come out somewhat smaller or larger than the average you set, and the container adds a small overhead.

## Fitting a size limit

Work backwards: the size limit, less the audio, spread over the length, is the video bitrate that fits. Export a little under it to leave room for the overhead and the variation.

If the audio alone fills the limit, the video is too long for that size at that audio bitrate. Lower the audio bitrate or split the video.

## Sources

- [YouTube Help: Recommended upload encoding settings](https://support.google.com/youtube/answer/1722171)

## Questions

### How do I calculate a video's file size?

Add the video and audio bitrates, multiply by the length in seconds and divide by 8. The calculator does it as you type.

### How big is a one-minute 1080p video?

At YouTube's recommended 8 Mbps for 1080p at up to 30 fps, plus 128 kbps audio, about 58 MB.

### What bitrate fits a 100 MB file?

It depends on the length. For a two-minute video with 128 kbps audio it's about 6.9 Mbps of video. Switch to “Bitrate from file size” and enter your own length.

### Why is my exported file a different size?

Encoders vary the bitrate from scene to scene, and the container adds a little. The calculation gives the size at the average bitrate.

### Which MB does it use?

1,048,576 bytes, as Windows counts. macOS counts 1,000,000 bytes, so it shows the same file as slightly larger.