Video File Size Calculator

Estimated file size (MB) —

Size in GB (10⁹ bytes): —
Size in GiB (2³⁰ bytes): —
Combined bitrate (kbps): —
MB per minute: —
Video share of the file: —

A video's file size is its combined bitrate multiplied by its duration, divided by 8 to turn bits into bytes. Ten minutes of 5 Mbps video with 128 kbps audio is 5,128 kbps × 600 s ÷ 8 = 384,600 kB, or about 384.6 MB. Container overhead usually adds only one or two percent on top.

About this tool

Editors planning an export, streamers sizing a recording drive and anyone squeezing a clip under an upload cap all run the same sum: bitrate times time. Enter the video bitrate in megabits per second, the audio bitrate in kilobits per second and the running time, and the calculator returns the size in decimal megabytes, decimal gigabytes and binary gibibytes, plus the megabytes each minute costs and how much of the file the picture takes up. It also flags files above 4 GiB, which FAT32 storage cannot hold as one file. The figure assumes a constant bitrate. Variable-bitrate encodes land near the average you enter, but a scene-heavy clip can come out a few percent larger or smaller, and container overhead adds a little more.

How to use it

Enter the video bitrate
Type the target or measured video bitrate in Mbps, as shown in your encoder settings or a media inspector.
Add the audio bitrate
Enter the audio track's bitrate in kbps, such as 128 or 320; set it to 0 for a silent clip.
Set the running time
Use the hour and minute steppers and type the remaining seconds.
Read the sizes
The headline is in MB; the stats give GB, GiB, MB per minute and the video share of the total.

Examples

8 Mbps video, one minute

Video bitrate: 8
Audio bitrate: 0
Hours: 0
Minutes: 1
Seconds: 0

Result Estimated file size (MB): 60
Size in GB (10⁹ bytes): 0.06
Size in GiB (2³⁰ bytes): 0.056
Combined bitrate (kbps): 8,000
MB per minute: 60
Video share of the file: 100%

Duration = 0 h × 3600 + 1 min × 60 + 0 s = 60 s
Total bitrate = 8 Mbps × 1000 + 0 kbps = 8000 kbps
Size = 8000 kbps × 60 s ÷ 8 = 60000 kB
In megabytes: 60000 kB ÷ 1000 = 60 MB

A one-minute 1080p clip at YouTube's suggested 8 Mbps with the audio left out comes to 60 MB, so every minute at this rate adds another 60 MB.

10-minute 720p upload

Video bitrate: 5
Audio bitrate: 128
Hours: 0
Minutes: 10
Seconds: 0

Result Estimated file size (MB): 384.6
Size in GB (10⁹ bytes): 0.385
Size in GiB (2³⁰ bytes): 0.358
Combined bitrate (kbps): 5,128
MB per minute: 38.46
Video share of the file: 97.5%

Duration = 0 h × 3600 + 10 min × 60 + 0 s = 600 s
Total bitrate = 5 Mbps × 1000 + 128 kbps = 5128 kbps
Size = 5128 kbps × 600 s ÷ 8 = 384600 kB
In megabytes: 384600 kB ÷ 1000 = 384.6 MB

5 Mbps of video and a 128 kbps AAC track for ten minutes adds up to about 385 MB; the audio is only 2.5% of that.

One-hour 4K recording

Video bitrate: 20
Audio bitrate: 320
Hours: 1
Minutes: 0
Seconds: 0

Result Estimated file size (MB): 9,144
Size in GB (10⁹ bytes): 9.144
Size in GiB (2³⁰ bytes): 8.516
Combined bitrate (kbps): 20,320
MB per minute: 152.4
Video share of the file: 98.4%

Duration = 1 h × 3600 + 0 min × 60 + 0 s = 3600 s
Total bitrate = 20 Mbps × 1000 + 320 kbps = 20320 kbps
Size = 20320 kbps × 3600 s ÷ 8 = 9144000 kB
In megabytes: 9144000 kB ÷ 1000 = 9144 MB

An hour at 20 Mbps with 320 kbps audio is about 9.1 GB, more than twice the 4 GiB single-file limit of a FAT32 card.

How it is calculated

Size (bytes) = (V × 1,000,000 + A × 1,000) × t ÷ 8

V: Video bitrate in megabits per second
A: Audio bitrate in kilobits per second
t: Running time, measured as a count of seconds

Bitrates are quoted in bits per second with decimal SI prefixes, so 1 Mbps is one million bits each second. Adding the video and audio streams gives the total bits per second; multiplying by the running time gives total bits, and dividing by 8 gives bytes. Decimal MB and GB divide by 10⁶ and 10⁹, which matches how drive makers and macOS report sizes. Windows Explorer reports binary units, so the GiB figure divides by 1,073,741,824 instead.

When not to use it

For quality-based encodes such as CRF, where the bitrate is not known until the encode finishes.
For uncompressed or image-sequence footage, which is sized per frame rather than by bitrate.
When an upload limit is tight to the last megabyte, since container overhead is not included.

Common mistakes

Mixing up megabits and megabytes: 8 Mbps is only 1 MB per second.
Entering the audio bitrate in Mbps, which makes the audio share a thousand times too large.
Comparing the GB figure with Windows Explorer, which shows GiB labelled as GB.

Frequently asked questions

Why is my exported file a little larger than the estimate?

Containers such as MP4 and MKV store headers, indexes and timestamps alongside the streams. That overhead is usually around 1 to 2 percent. Variable-bitrate encoders also overshoot the target on busy scenes, so a final file can land a few percent above the plain bitrate-times-time figure.

What bitrate does a 1080p video usually use?

YouTube's upload guidance lists about 8 Mbps for 1080p at 24 to 30 fps and 12 Mbps at 48 to 60 fps for standard dynamic range. Streaming services deliver much less, often 3 to 6 Mbps, because they use more efficient codecs and heavier compression.

What is the difference between GB and GiB here?

A GB is 1,000,000,000 bytes and a GiB is 1,073,741,824 bytes, about 7.4 percent more. Storage packaging and macOS use GB; Windows reports GiB but labels it GB. The calculator shows both so you can match whichever number your system displays.

How do I find the bitrate of an existing video?

Media inspectors such as MediaInfo list the overall and per-stream bitrates. You can also divide the file size in bits by the running time counted as seconds: a 300 MB file lasting 5 minutes averages 300 × 8 ÷ 300 = 8 Mbps across all streams.

Does the codec change the file size?

Not for a given bitrate. H.264, HEVC and AV1 at 8 Mbps all produce the same size per second. The codec changes the quality you get at that bitrate, which is why HEVC or AV1 can reach a similar picture at a lower bitrate and so a smaller file.

Why does the calculator warn above 4 GiB?

FAT32, still common on older SD cards and USB sticks, cannot store a single file larger than 4 GiB minus one byte. Many cameras split recordings at that size for this reason. exFAT and NTFS do not have this limit.

Cite this tool

Using this tool in an assignment, article or report? Copy a citation, or a link for your website.

APA

Tools Directory Editorial Team. (2026, October 18). Video File Size Calculator. Tools Directory. Retrieved October 26, 2026, from https://tools.milunir.com/video-audio/media-utilities/video-file-size-calculator/

MLA

Tools Directory Editorial Team. “Video File Size Calculator.” Tools Directory, 18 Oct. 2026, https://tools.milunir.com/video-audio/media-utilities/video-file-size-calculator/. Accessed 26 Oct. 2026.

Chicago

Tools Directory Editorial Team. “Video File Size Calculator.” Tools Directory. Last modified October 18, 2026. Accessed October 26, 2026. https://tools.milunir.com/video-audio/media-utilities/video-file-size-calculator/.

Link

<a href="https://tools.milunir.com/video-audio/media-utilities/video-file-size-calculator/">Video File Size Calculator – Tools Directory</a>