Video Bitrate Calculator | File Size Estimator

Video bitrate calculator: turn bitrate and length into file size, or find the bitrate that fits a 20 MB Discord limit, with an ffmpeg two-pass command. Free.

Also known as: video bitrate calculator · video file size calculator · bitrate to file size calculator · discord video size calculator · video size calculator 4k · mbps to mb calculator · ffmpeg target file size · youtube bitrate calculator · h264 bitrate calculator

unit converters

social media tools

calculators

Video Settings

bitrate to size

I want to know

Length

seconds, m:ss or h:mm:ss

Frame rate

sets MP4 overhead and YouTube's table

Audio bitrate (kbps)

128 is typical for AAC stereo; 0 = no audio

Use YouTube's recommendation

SDR, 24-30 fps; fills the bitrate below

Video bitrate

average bitrate of the video stream

Unit

1 Mbps = 1,000 kbps

File size = (video bitrate + audio bitrate) x length / 8, plus the MP4 index ffmpeg writes: about 2 KB and 12 bytes per frame.

Checked by encoding real clips with ffmpeg 9.0.2: two-pass encodes landed within 1.13% of the predicted size, and a 3% margin kept all of them under the limit.

File Size

The file size, what each stream contributes and the same length at YouTube's recommended bitrates will appear here.

About Video Bitrate Calculator

A video bitrate calculator converts between bitrate, length and file size. Enter a bitrate and a duration to see how big the file will be, or pick a size limit such as Discord's 20 MB and get the highest video bitrate that fits, with a two-pass ffmpeg command to encode it and YouTube's recommended upload bitrates for comparison.

Key Features

File size from video bitrate, audio bitrate and length, including the MP4 container overhead
Reverse mode: the highest bitrate that fits a 20 MB Discord, 25 MB Gmail or custom limit
Two-pass ffmpeg command with the bitrate filled in, tested to land under the target
YouTube's recommended upload bitrates from 360p to 8K at standard and high frame rates
Sizes in MB and GB as uploads count them, and in MiB and GiB as Windows shows them
Accepts lengths as seconds, minutes and seconds, or hours, minutes and seconds

Use Cases

Fit a 2-minute gameplay clip under Discord's 20 MB free upload limit
Estimate how much space a week of 1080p security camera footage needs
Plan drive space for a 2-hour 4K wedding video project before a shoot
Pick an upload bitrate that meets YouTube's 1080p 60 fps recommendation
Shrink a product demo so it goes out as a 25 MB Gmail attachment
Budget storage for a library of training videos before moving it to the cloud

Supported Formats

kbps and Mbps

MB, GB, MiB, GiB

MP4 (H.264 and AAC)

24 to 60 fps

Related Keywords

video bitrate calculator

video file size calculator

bitrate to file size calculator

discord video size calculator

video size calculator 4k

mbps to mb calculator

ffmpeg target file size

youtube bitrate calculator

h264 bitrate calculator

How do you calculate video file size from bitrate?

Add the video and audio bitrates, multiply by the length in seconds and divide by 8 to turn bits into bytes. A 10-minute video at 8 Mbps with 128 kbps audio is (8,000 + 128) kbps x 600 seconds / 8 = 609.6 MB, plus about 0.6 MB that the MP4 container uses to index every frame. Bitrates and upload limits are decimal, so 1 MB is 1,000,000 bytes, while Windows Explorer shows binary units and lists the same file as 581.9 MB. Encoders aim for the average bitrate rather than hit it exactly, so leave a few percent of headroom when a file has to fit under a hard limit.

Privacy & Security

All processing happens locally in your browser. Your data never leaves your computer, ensuring complete privacy and security.

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Frequently asked questions

What is Video Bitrate Calculator used for?

Video bitrate calculator: turn bitrate and length into file size, or find the bitrate that fits a 20 MB Discord limit, with an ffmpeg two-pass command. Free.

Is Video Bitrate Calculator free to use?

Yes. Video Bitrate Calculator is completely free with no usage limits, and there is no paid tier required to use it.

Do I need an account to use Video Bitrate Calculator?

No. Video Bitrate Calculator works immediately in your browser with no signup, login, or email address required.

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