File size: a tutorial
To many people, file size is a black art. Worse, for many, file size just does not feature on their radar at all.
File size is how big a piece of digital information/ a digital asset is, i.e. how much storage, memory and bandwidth it consumes. File size impacts on performance: the bigger something is, typically the slower it will be to open, be it a Word document, a large picture or similar. File size is an issue when putting things on the web, as the bigger a file is, the longer it takes to download for the end user. Equally, it can impact on email in a big way.
To many people, file size is a black art.
Units of size:
The basic unit of file size is the kilobyte (KB). This is 1024 bytes, each of which is madeup of 8 bits and represents a single character.
You'll often see files expressed in terms of kilobytes and for larger files, megabytes. A megabyte (MB) is 1024 kilobytes. Nowadays, the specs for computers are quoted in terms of Gigabytes, which are 1000 megabytes, or a million kilobytes.
So below, we've put together a ready reckoner of typical file sizes for various digital assets.
The File Size Ready Reckoner *
|file type||comments||file size|
|.txt||1 page of plain text||4KB|
|.doc||1 formatted page, no images||29KB|
|.xls||Typical 1 page spreadsheet||18KB|
|.mp3||typical 5 minute song||6MB|
|.wmv||1 minute movie for youtube (low quality)||2.5MB|
|.html||typical web page||50KB|
|.jpg||1500x900 pixels - i.e. 5"x3"||800KB|
|.jpg||200x300 pixels - typical for the web||15KB|
* all quoted file sizes are approximate.
Other Typical examples
An album of mp3s - 100MB
A 2 hour feature film - 600MB