Video Bitrate & File Size Calculator
Calculate video bitrate, file size, or recording time from the other two. Free bitrate calculator with container overhead guidance, no file needed, runs in your browser.
What this tool does
This bitrate calculator turns a target into numbers you can set in an encoder: enter any two of bitrate, file size, and duration, and it gives you the third. It runs in the browser, needs no file, and takes seconds.
Use it before an export to hit an upload limit, before a recording to plan storage, or to check that a delivery spec is realistic for your footage.
How it works
- Choose what you want to find: bitrate, file size, or duration.
- Enter the values you already know.
- The answer appears instantly, with headroom guidance for container overhead.
Supported formats
No file input: everything runs in your browser. Nothing is uploaded.
When to use it
Hit an upload limit
Work backwards from a size cap to the bitrate that fits it, before you waste an export.
Plan a recording
Convert a card or drive capacity into minutes of footage at a given quality.
Set export settings
Translate a target file size into a bitrate your editor will accept.
Check a delivery spec
Confirm a requested size is realistic for the duration before committing to it.
The math, done for you
Bitrate, file size, and duration are three sides of one equation: size equals bitrate multiplied by time. Fix any two and the third is determined. The calculator does that arithmetic instantly and adds the container overhead guidance that raw math leaves out.
The results are planning numbers. Real encoders vary: motion, scene cuts, and codec settings all push the final file a few percent away from the prediction. The tool says so directly rather than implying false precision, and the headroom note absorbs most of the variance.
No file is needed and nothing is uploaded. It is a calculator that runs in the browser, in the same spirit as the rest of this site.
Frequently asked questions
Why did my exported file end up bigger than the calculation?
Container overhead plus how the encoder spends its bits: audio adds its own track, and complex scenes get more data than the average. Leave the suggested headroom and you land within a few percent. Exact sizing is an encoder feature, not a math feature.
How accurate is it?
The arithmetic is exact; the prediction is not, because real encoders are not constant-rate machines. Treat the result as a target, not a guarantee, and use the headroom note when a cap is involved.
What bitrate should I use for YouTube?
Check the platform requirements with the Video Compatibility Checker, then come back here to see what file size that bitrate produces for your duration.
Does it work for audio files?
Yes. The same size-equals-bitrate-times-time relation holds for audio; enter the audio bitrate and duration and the calculator does the rest.
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Privacy
Your file never leaves your device.
Platform and product names are used descriptively for reference only; LimkaKit is not affiliated with or endorsed by YouTube, Instagram, TikTok, Adobe, or Blackmagic Design.