Video File Size Calculator

Written byOleh Soloninupdated 5 October 2026

What to work out

Video bitrate, Mbps

Audio bitrate, kbps

Duration, minutes

Result

File size, MB1,889.4
Video bitrate, Mbps25
In GB (10⁹ bytes)1.889
In GiB — what Windows shows1.76
Per minute, MB188.94
Total bitrate, Mbps25.19
Audio share, %0.8%

Bitrate times time

Works out video file size from bitrate and running time, and the reverse — the bitrate needed to fit a given file size.

Video size is set neither by resolution nor by duration on their own but by bitrate — data per second. Eight megabits a second for a minute gives sixty megabytes whether the footage is 1080p or 4K.

The one catch is the division by eight: bitrate is measured in bits and file size in bytes. Then there is audio, which next to video barely registers — 192 kilobits against 25 megabits is under one percent of the file.

How to use

Enter the video bitrate in megabits per second.
Add the audio bitrate in kilobits.
Enter the length in minutes.
For the reverse problem, set a target size and the calculator finds the bitrate that fits it.

What bitrate costs over ten minutes

Each row is a run of this calculator at ten minutes of footage with audio at 192 kbit/s. Size grows in step with bitrate: double it and the file doubles.

The last column explains why nobody thinks about the audio. At 8 Mbit/s it takes 2.3 percent of the file; at 100 Mbit/s, two tenths of a percent. Saving on audio is almost never worth it: it is cheap and the difference is audible immediately.

Runs of this calculator at ten minutes of footage with audio at 192 kbit/s.
Video bitrate	Size over 10 minutes	In gigabytes	Per minute	Audio share
8 Mbit/s	614 MB	0.614	61 MB	2.3%
25 Mbit/s	1,889 MB	1.889	189 MB	0.8%
50 Mbit/s	3,764 MB	3.764	376 MB	0.4%
100 Mbit/s	7,514 MB	7.514	751 MB	0.2%

What this calculator shows

File size in megabytes and gigabytes, and the weight of one minute
The reverse: the bitrate that fits a target file size
The share of the file taken by audio

What to keep in mind

For variable bitrate, enter the average: the file size follows the average stream over the whole length, and the peak cannot give it.
Take the bitrate from the codec settings or the platform's requirements: resolution alone sets neither the stream nor the file size.

FAQs

How big is an hour of video?

At 8 Mbps about 3.6 GB, at 25 Mbps roughly 11.3 GB, and at 100 Mbps around 45 GB.

What bitrate does 1080p need?

8 to 12 Mbps is fine for viewing; recording for an edit uses 50 and up so that colour grading does not fall apart.

How do I fit a video into a size limit?

Divide the target megabytes by the running time in seconds and multiply by eight — that gives the total bitrate in megabits you can afford.

Does resolution affect file size?

Only indirectly. Bitrate sets the size, but 4K at a low bitrate looks worse than 1080p at the same one — which is why higher resolutions get higher bitrates.

How do I turn bitrate into file size?

Multiply the megabits by the seconds and divide by eight — there are eight bits in a byte. 25 Mbit/s over ten minutes is 25 × 600 ÷ 8 = 1,875 megabytes, plus audio.

Why does Windows show fewer gigabytes?

Because Windows counts in gibibytes — 2³⁰ bytes each — and labels them "GB". The calculator shows both: 1,889.4 MB is 1.889 GB of 10⁹ bytes and 1.76 GiB, which Windows displays as "1.76 GB".

Worked example

Ten minutes of 4K

Input: 25 Mbps video, 192 kbps audio, 10 minutes

Output: 1,889 MB, which is 1.85 GB

Note: Almost two gigabytes for ten minutes. Audio takes under one percent of that — economising on it is pointless, and the difference is audible immediately.

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Result

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