Why Are Hard Drives Capacity Less Than Advertised?

[geokilla]

I remember LTT did a video on this but I forgot what it's called. May someone share it? Want to use it to explain to my friends.

[Slottr]

Windows measures in Tebibytes, not Terabytes - if that is what you are referencing 

[RONOTHAN##]

Don't remember there ever being a video on it, but the short answer is a difference in how Gigabytes are defines. Hard drive vendors use the decimal definition of a Gigabyte (10^9 bytes), while Microsoft and a lot of other software will use the binary definition of a Gigabyte (2^30 bytes). Due to the difference in definitions, software under reports capacity. 

 

To ease confusion, the binary definition has been renamed to Gibibytes, Mebibytes, Tebibytes, etc., though Microsoft and most other people still mislabel which one they're talking about. 

[Guest]

14 minutes ago, geokilla said:

I remember LTT did a video on this but I forgot what it's called. May someone share it? Want to use it to explain to my friends.

Windows reserves space for the OS

[ToboRobot]

Marketing departments are butt-heads and have more say than engineering.

[tikker]

Was it this Techquickie perhaps?

 

It is misuse of prefixes. Giga is the SI prefix defined for the decimal system, meaning "a billion" or 10 raised to the 9th power. If you report that number in the binary system then it appears lower, because you are no longer reporting actual gigabytes, but a base 2 equivalent. Note that it is the same number, just represented differently. 1000 gigabyte is 931 gibibyte. The confusion starts when OSes, for example, start reporting it as 931 gigabyte, since it is technically the wrong prefix.

[geokilla]

13 minutes ago, tikker said:

Was it this Techquickie perhaps?

 

It is misuse of prefixes. Giga is the SI prefix defined for the decimal system, meaning "a billion" or 10 raised to the 9th power. If you report that number in the binary system then it appears lower, because you are no longer reporting actual gigabytes, but a base 2 equivalent. Note that it is the same number, just represented differently. 1000 gigabyte is 931 gibibyte. The confusion starts when OSes, for example, start reporting it as 931 gigabyte, since it is technically the wrong prefix.

That's the one! Thanks!

[ewitte]

2 hours ago, Slottr said:

Windows measures in Tebibytes, not Terabytes - if that is what you are referencing 

The confusing part is they ended up terming "Tebibytes" after decades where 99% (everything except hard drives) listed as Terabytes.

[Doobeedoo]

I wish this would be rectified from drive and OS manufacturers though.