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Video Bitrate Calculator

Video & AudioMedia Utilities

All audio tracks combined.

Video bitrate (kbps) —
Total bitrate (kbps)
—
Video bitrate (Mbps)
—
Space taken by audio (MB)
—
Duration
—

Video bitrate is the file size in kilobits divided by the running time (counted as seconds), minus the audio bitrate. A 700 MB file holding a 90-minute film has 5,600,000 kbit to spend over 5,400 seconds, or 1,037 kbps in total; with 128 kbps audio the video stream can use about 909 kbps.

About this tool

Two-pass encoding, upload caps on messaging apps and course platforms, and fixed-size archive discs all start from the same question: how many kilobits per second can the picture have if the finished file must not exceed a given size? This calculator takes the size limit (decimal MB and GB or binary MiB and GiB), the running time split into hours, minutes and seconds, and the audio bitrate, then returns the video bitrate in kbps and Mbps, the total bitrate, and how many megabytes the audio track will occupy. The working is listed line by line so you can paste the figure into FFmpeg, HandBrake or an NLE export dialog. It does not judge quality: the same bitrate looks very different in H.264, HEVC and AV1, and container overhead of a percent or two is not subtracted.

How to use it

  1. Set the size limit

    Type the largest file you can accept and pick MB, GB, MiB or GiB from the unit list inside the field. Upload limits are usually decimal; FFmpeg and many Linux tools count in binary units.

  2. Enter the running time

    Fill in hours, minutes and seconds. Any of them can stay at zero, and minutes above 59 are accepted.

  3. Add the audio bitrate

    Enter the combined bitrate of every audio track, for example 128 kbps for stereo AAC or 640 kbps for AC-3 5.1.

  4. Read the video bitrate

    The headline figure is the kbps to give the video encoder. Set it a little lower to leave room for container overhead.

Examples

200 MiB for a 10-minute clip

Target file size
200
Size unit
MiB
Hours
0
Minutes
10
Seconds
0
Audio bitrate
128

Result Video bitrate (kbps): 2,602.7
Total bitrate (kbps): 2,730.7
Video bitrate (Mbps): 2.6
Space taken by audio (MB): 9.6
Duration: 10 min

  1. Duration = 600 s
  2. Size = 200 MIB × 8192 kbit = 1638400 kbit
  3. Total bitrate = 1638400 ÷ 600 = 2730.67 kbps
  4. Video bitrate = 2730.67 − 128 = 2602.67 kbps

The FFmpeg H.264 guide's own case: 2,730.7 kbps overall, and after 128 kbps of AAC audio about 2.6 Mbps is left for the picture.

90-minute film on a 700 MB CD

Target file size
700
Size unit
MB
Hours
1
Minutes
30
Seconds
0
Audio bitrate
128

Result Video bitrate (kbps): 909
Total bitrate (kbps): 1,037
Video bitrate (Mbps): 0.91
Space taken by audio (MB): 86.4
Duration: 1 h 30 min

  1. Duration = 5400 s
  2. Size = 700 MB × 8000 kbit = 5600000 kbit
  3. Total bitrate = 5600000 ÷ 5400 = 1037.04 kbps
  4. Video bitrate = 1037.04 − 128 = 909.04 kbps

700 MB is 5,600,000 kbit; spread over 5,400 s that is 1,037 kbps, and 909 kbps remain once 128 kbps stereo audio is taken out.

45-minute lecture under 2 GB

Target file size
2
Size unit
GB
Hours
0
Minutes
45
Seconds
0
Audio bitrate
192

Result Video bitrate (kbps): 5,733.9
Total bitrate (kbps): 5,925.9
Video bitrate (Mbps): 5.73
Space taken by audio (MB): 64.8
Duration: 45 min

  1. Duration = 2700 s
  2. Size = 2 GB × 8000000 kbit = 16000000 kbit
  3. Total bitrate = 16000000 ÷ 2700 = 5925.93 kbps
  4. Video bitrate = 5925.93 − 192 = 5733.93 kbps

16,000,000 kbit over 2,700 s is 5,925.9 kbps; with 192 kbps audio the video can run at about 5.7 Mbps.

How it is calculated

video kbps = (S × k) ÷ t − a

S
target file size in the chosen unit
k
kilobits per unit: 8,000 for MB, 8,000,000 for GB, 8,192 for MiB, 8,388,608 for GiB
t
duration, counted as seconds
a
audio bitrate in kbps

A byte is 8 bits and encoders count kilobits as 1,000 bits, so a decimal megabyte is 8,000 kbit and a mebibyte (1,048,576 bytes) is 8,192 kbit. Dividing the total kilobits by the seconds gives the average bitrate the whole file may use. The audio stream takes its share first, and what remains is the average video bitrate. This is the calculation the FFmpeg H.264 guide gives for two-pass encoding to a target size.

When not to use it

  • Constant-quality encodes (CRF or CQ) ignore a target bitrate, so the figure will not control their size.
  • Live streaming needs a bitrate set by upload bandwidth, not by a file size.
  • Very short clips under a few seconds are dominated by container headers, so the estimate drifts.

Common mistakes

  • Mixing MB and MiB: a 4 GB limit is about 7% smaller than 4 GiB.
  • Forgetting extra audio tracks such as commentary or a second language.
  • Entering the result in Mbps where the encoder expects kbps, or the reverse.
  • Targeting the exact limit with no headroom, so the muxed file ends up a few megabytes over.

Frequently asked questions

Why is my encoded file slightly larger than the target?

The MP4 or MKV container stores indexes, timestamps and metadata on top of the audio and video streams, typically 1 to 2 percent of the file. Rate control in single-pass mode also overshoots now and then. Two-pass encoding hits the average closely, and shaving 2 percent off the video bitrate usually keeps the result under the cap.

What is the difference between MB and MiB here?

A megabyte (MB) is 1,000,000 bytes and a mebibyte (MiB) is 1,048,576 bytes. Windows Explorer labels binary sizes as MB, while upload services and drive makers use decimal units. Pick the unit your limit is actually stated in; the gap grows to about 7.4 percent at the gigabyte scale.

Does the codec change the bitrate this gives?

No. The arithmetic only shares out the available bits over time. The codec decides how good the picture looks at that rate: HEVC and AV1 typically reach the quality of H.264 at roughly 30 to 50 percent less bitrate, so a tight budget favours newer codecs if your playback devices support them.

How much audio bitrate should I set aside?

Stereo AAC at 128 kbps is a common default for speech and general video, 192 to 256 kbps for music-heavy content, and Opus sounds good at 96 kbps. Surround tracks such as AC-3 5.1 often run at 384 to 640 kbps, which can take a large slice of a small file.

Is the result an average or a maximum bitrate?

It is the average over the whole running time. In two-pass or ABR mode the encoder lets complex scenes go above it and simple scenes drop below, as long as the average holds. If a platform also caps peak bitrate, set a maxrate and buffer size in the encoder alongside this figure.

Can I use this to check what bitrate an existing file has?

Yes. Enter the file's size, its duration and its audio bitrate, and the result is the average video bitrate it was encoded at, give or take the container overhead.

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 Bitrate Calculator. Tools Directory. Retrieved October 27, 2026, from https://tools.milunir.com/video-audio/media-utilities/video-bitrate-calculator/

MLA

Tools Directory Editorial Team. “Video Bitrate Calculator.” Tools Directory, 18 Oct. 2026, https://tools.milunir.com/video-audio/media-utilities/video-bitrate-calculator/. Accessed 27 Oct. 2026.

Chicago

Tools Directory Editorial Team. “Video Bitrate Calculator.” Tools Directory. Last modified October 18, 2026. Accessed October 27, 2026. https://tools.milunir.com/video-audio/media-utilities/video-bitrate-calculator/.

Link<a href="https://tools.milunir.com/video-audio/media-utilities/video-bitrate-calculator/">Video Bitrate Calculator – Tools Directory</a>