Video Recording Size Calculator
Video recording size calculator works out File size and File size as an operating system reports it from Total bit rate (video plus audio), Recording length and Card or drive capacity. The default figures on this page give file size of 3,600.000 MB; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
3 steps
- File size = 8 Mbit/s x 3600 s / 8 = 3600 MB (3.6 GB).
- No capacity given, so nothing is fitted into a card or drive.
- Continuous recording uses 3600 MB per hour.
Its 5 worked examples are re-run on every release, last on 15 September 2026. What changed
Sources and references
3 sources
What the video recording size calculator calculates
Converts a video bit rate and duration into a file size, and works out how many such recordings fit in a given card or drive capacity, how much space is left over, and how many hours of footage the capacity holds.
How to use this video recording size calculator
Enter Total bit rate (video plus audio), Recording length, Card or drive capacity and Size of one file (overrides the computed size). File size updates as you type, and “Use a worked example” loads checked figures you can adjust. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind File size, File size as an operating system reports it and File size used for the fit calculation.
The method follows Definition of the bit rate: file size = bit rate x duration, with 8 bits to the byte, IEC 80000-13, Quantities and units - Information science and technology and Researched engineering contracts R773 (VIDEO-STORAGE) and R2159 (whole files in a capacity).
Research fixture R773-GT-1: 8 Mbit/s for 60 seconds example
With Total bit rate (video plus audio): 8, Recording length: 60, the calculator returns File size: 60, File size: 0.06. This example is checked against an independent source in the test suite.
What you can compare
Change one input at a time to see how it affects File size, File size as an operating system reports it and File size used for the fit calculation. The inputs you can vary are Total bit rate (video plus audio), Recording length, Card or drive capacity, Size of one file (overrides the computed size) and Number of streams or cameras.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
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Frequently asked questions
How big is 30 minutes of 1080p video?
Converts a video bit rate and duration into a file size, and works out how many such recordings fit in a given card or drive capacity, how much space is left over, and how many hours of footage the capacity holds. Open “How this is worked out” beside the result to see each step for your own figures.
How to calculate video file size?
It needs Total bit rate (video plus audio), Recording length, Card or drive capacity, Size of one file (overrides the computed size) and Number of streams or cameras. Nothing else is required, and the figures stay in your browser.
How many GB would a 20 minute video be?
On the figures this page opens with — total bit rate (video plus audio) 8 Mbit/s and recording length 60 s — the file size is 3,600 MB. No single number fits everyone: change any figure above and the answer updates as you type, with each step of the arithmetic beside it.
How big is 10 minutes of 4K video?
The result gives File size, File size as an operating system reports it, File size used for the fit calculation, Whole files that fit, Space left over and Recording time the capacity holds, each labelled with its unit so the figure can be read on its own.
What information do I need for the video recording size calculator?
You need Total bit rate (video plus audio), Recording length, Card or drive capacity, Size of one file (overrides the computed size) and Number of streams or cameras. The page opens with default figures that give file size of 3,600.000 MB, so you can see the scale before entering your own.
What does this video recording size calculator show?
It shows File size, File size as an operating system reports it, File size used for the fit calculation, Whole files that fit, Space left over, Recording time the capacity holds and Storage per hour of recording, with the working and any warnings for your entries.