Size On Disk

Files are stored on the disk in what is called called clusters (a group of disk sectors). Size on disk refers to the amount of cluster allocation a file is taking up, compared to file size which is an actual byte count.

The lowest cluster size for FAT32 is 1, so if the actual file only needs a small portion of the cluster, the size on disk for that file will reflect the entire cluster as being used. This is why when you check the properties tab of a file (using Microsoft Windows), you will usually see the size on disk size is larger than the file size.

size vs size on disk
Image: File size vs. size on disk.

Also see related terms cluster and file.

Vangie Beal
Vangie Beal
Vangie Beal is a freelance business and technology writer covering Internet technologies and online business since the late '90s.

Top Articles

Huge List Of Texting and Online Chat Abbreviations

From A3 to ZZZ we list 1,559 text message and online chat abbreviations to help you translate and understand today's texting lingo. Includes Top...

How To Create A Desktop Shortcut To A Website

This Webopedia guide will show you how to create a desktop shortcut to a website using Firefox, Chrome or Internet Explorer (IE). Creating a desktop...

The History Of Windows Operating Systems

Microsoft Windows is a family of operating systems. We look at the history of Microsoft's Windows operating systems (Windows OS) from 1985 to present...

Hotmail [Outlook] Email Accounts

  By Vangie Beal Hotmail is one of the first public webmail services that can be accessed from any web browser. Prior to Hotmail and its...

Unregulated Power Supply Definition...

An unregulated power supply is a system that transforms input voltage into direct...

Cybersecurity Awareness Training Definition...

Cybersecurity awareness training informs employees of the attack surfaces and vectors in their...

OST File Definition &...

An OST file, or offline storage table (.ost) file, is an Offline Outlook...