How to calculate raw uncompressed video sizes

This short text will tell you how to calculate the size of a video in memory and on disk. This short text is really an introduction. It will give you basic terminology and tools to give you an idea of the numbers we are working with. If you work with video you probably already know this and can skip through to the video size calculator at the bottom. If you do not know this well just read on…

Video frame pixel size

When we talk about the video frame size we talk about how many pixels we see on the video screen. A larger frame size gives better quality and a larger file. To determine how many pixels each frame is you simply multiply the width in pixels by the height in pixels to get the total number of pixels. A typical 640×480 TV frame (not HD) is 307200 pixels or about 0.3 MPixels. If you would save one such file in an uncompressed image format, like BMP, you would get a file at least 300kb large.

Video frame byte size

If we want to show our video in colour we need to use three colour channels to represent the one pixel. Today we almost always use one byte per colour channel, and although we use different color spaces we most often need three color channels. To get the raw uncompressed size of the video frame you then need to multiply the number of pixels in the video frame by 3 to get the number of bytes each video frame will take. You now have the size of the uncompressed video frame, in our example 0.9 Megabyte.

Raw video size

We now know everything we need to calculate how large an uncompressed video file will be. We now how large one video frame is and we know how many frames are used every second. Let us continue out example of a video in 640×480 where each frame took 0.9 Megabyte running at 25 frames per second. The size of one second video footage would then require 25*0.9=22.5 Mb. An normal movie running one and a half hour would require 90*60*22.5 = 121500 MB = 118 Gb or about 26 single layer DVDs. The obvious conclusion is that when you work with videos you require a lot of free disk space and you need take make it smaller with compression when you have finished creating a video.

Video size calculator

Enter the resolution of your video to find out its uncompressed size.

Free Video size calculator – © Fredrik Lönn 2008
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