Video File Size Calculator

Estimate a video’s file size from its bitrate, audio and duration, or work out the bitrate that fits a target size. Calculated in your browser.

Or fit a target file size:

Estimated file size

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In megabytes-
Video bitrate to hit target-

Show the math

File size is the combined bitrate over the duration, converted from bits to bytes:

MB = (video Mbps + audio Mbps) × seconds ÷ 8

Sizes use decimal units (1 GB = 1,000 MB), matching how storage and uploads are usually quoted.

Everything is calculated in your browser.

What this does

A video file size calculator estimates a video’s size from its bitrate, audio, and duration, or works out the bitrate that fits a target size.

How to use it

  1. Enter the video bitrate.
  2. Add the audio bitrate.
  3. Set the duration.
  4. Read the file size, or solve for bitrate.

How it works

File size is the combined bitrate over the duration, converted from bits to bytes. Sizes use decimal units (1 GB = 1,000 MB), matching how storage and upload limits are quoted.

MB = (video + audio Mbps) × seconds ÷ 8

Understanding your result

Size is simply the combined video and audio bitrate carried over the duration, so the lever you control is bitrate: to hit a target size, the tool gives the bitrate that fits, and lowering it trades quality for a smaller file. Sizes use decimal units to match how upload caps and storage are quoted, so this is the right basis for checking a file will fit a platforms limit.

Example

10 Mbps video plus 0.2 Mbps audio for 10 minutes is about 765 MB.

Sources & methodology

Last updated .

Frequently asked questions

How is file size calculated?

It is the combined bitrate over the duration, converted from bits to bytes: MB = (video Mbps + audio Mbps) × seconds ÷ 8.

Are sizes in decimal or binary units?

Decimal (1 GB = 1,000 MB), matching how storage capacity and upload limits are usually quoted.

Is anything uploaded?

No. Everything is computed in your browser — nothing you enter leaves your device.