*New Forum, New Edit [4/11/06]*

This is a new thread, since the old one was lost when we switched to the new forums last fall/winter. Please feel free to add in!

Taken from the macrumors.com forums:

quote:

Here’s a formula to convert “retail size” to “actual size.” This assumes that the manufacturer is using 1GB = 1,000,000,000 bytes (instead of 1GB = 1,073,741,824 bytes as they should).

Actual Drive Size = Retail Drive Size * 0.931

This formula is an approximation. Many times they’ll round the drive size somewhat, but this gives you a rough idea of the real world space.

For Quick Reference:

36gb = 33.5gb

40gb = 37gb

60gb = 55gb

74gb = 69gb

80gb = 74gb

100gb = 93gb

120gb = 112gb

160gb = 149gb

200gb = 186gb

250gb = 233gb

300gb = 279gb

350gb = 326gb

400gb = 372gb

500gb = 465gb

These are rounded to the nearest gigabyte.
Hope you guys enjoy, let me know if theres any sizes you want added to the list.

[edited]

Thats spot on for my “74gb” raptor, “160gb” ATA and “250gb” SATA WD caviars.

spot on for the “60gb” drive i have here.

spot on for my 40GB and two 80GB drives and my 160GB RAID

windows is saying that the 3 120GB Maxtor Maxdiamond 10 I have are 114GB in size instead of the 112GB you posted

rest checked out perfectly

nice guide!

Funny, my 120GB Seagate external drive shows as 112GB

320GB should be 298GB then?

some manufacturers give you a little more than others and some times it depends on the batch or model as not all maxtors may give you what diablo is finding.

My Deskstar is a 250GB but after install it reflects 232GB.
My WD80GB Refelcts 74GB.
Scsi 15GB 13GB

I wonder if there’s going to be a backlash as the discrepancy becomes more and more visible?

Or will MS switch from binary to decimal?

years ago, we had someone return a 20GB hard drive because “we sold it to him as a 20GB and it isn’t.” and we apparently “stole some of the gigabytes!”.

<div class="FTQUOTE"><begin quote>Originally posted by: MrbLOB9000

years ago, we had someone return a 20GB hard drive because “we sold it to him as a 20GB and it isn’t.” and we apparently “stole some of the gigabytes!”.</end quote></div>
What explanation did you give? Was it a long or short affair? I imagine there are a great many uninformed people who are feeling cheated from their HD purchases.

<div class="FTQUOTE"><begin quote>Originally posted by: gwimby

This is a new thread, since the old one was lost when we switched to the new forums last fall/winter. Please feel free to add in!</end quote></div>

quimby,

You’re probably referring to the thread posted in January of 2005 by Digikid.

In that thread we tried to come up with a decent formula for converting the decimal size of HDs to their binary size.  The conclusion was:

1 B(bin)= 1B(dec)

Then taking away some space for indexing and maybe some for how the zones are set up, etc., the low level format size of a 200 GB drive would be less than 200 GB expressed in binary GBs and less than 186 GB expressed in decimal GBs.

A link to that January, 2005 thread is <a target=_blank class=ftalternatingbarlinklarge href="http://forums.sudhian.com/messageview.cfm?catid=18&threadid=70931&highlight_key=y">FORUMS > General Hardware > Formatted Capacity of a HDD</a>

If the link still works, you’ll see the thought process.

edit:  Added different format for link.
If the above doesn’t work, try this link:
FORUMS> General Hardware> Formatted Capacity of a HDD

Actually I had a thread exactly like this one, but it was lost during the last forum upgrade.
Doh!
But The Thread you’re referenceing rf 2ner has some great info, and def. sheds some more light on the subject. Thanks for the cross-linking!

Here are my HDD sizes, rounded to integers: 60 GB = 56 GB, 250 GB = 233 GB, 120 GB = 112 GB, 300 GB = 279 GB, so you got them quite right…