# CD Size **URL:** \ **Category:** Factual Questions\ **Created:** [March 25, 2004, 9:11am UTC](https://boards.straightdope.com/t/cd-size/236315 "2004-03-25T09:11:31Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![Ponster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ponster/32/17081_2.png) [@Ponster](https://boards.straightdope.com/u/Ponster)\ **Post date:** [March 25, 2004, 9:11am UTC](https://boards.straightdope.com/t/cd-size/236315/1 "2004-03-25T09:11:31Z")
Went off to the pub last night for a pub quiz (we even managed to win !) but one of the questions that I felt silly for getting wrong was : ?What is the size in Mbs of a standard CD?? I said 650Mb with a big smile on my face only to find that the ?correct? answer was 700Mb. Since I bought a DVD burner I haven?t bought so many cd?s but I still thought that the standard size was still 650Mb. How stupid am I? ---
**Author:** ![Ponster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ponster/32/17081_2.png) [@Ponster](https://boards.straightdope.com/u/Ponster)\ **Post date:** [March 25, 2004, 9:13am UTC](https://boards.straightdope.com/t/cd-size/236315/2 "2004-03-25T09:13:56Z")
And why is my keyboard printing a **?** for a **"** 🙂 ---
**Author:** ![Gavin\_G](https://avatars.discourse-cdn.com/v4/letter/g/45deac/32.png) [@Gavin\_G](https://boards.straightdope.com/u/Gavin_G)\ **Post date:** [March 25, 2004, 11:00am UTC](https://boards.straightdope.com/t/cd-size/236315/3 "2004-03-25T11:00:32Z")
> [@Ponster](#): > > Went off to the pub last night for a pub quiz (we even managed to win !) but one of the questions that I felt silly for getting wrong was : > ?What is the size in Mbs of a standard CD?? > I said 650Mb with a big smile on my face only to find that the ?correct? answer was 700Mb. Since I bought a DVD burner I haven?t bought so many cd?s but I still thought that the standard size was still 650Mb. > > How stupid am I? Hey! No fair, I agree with your answer. FWIW ---
**Author:** ![GorillaMan](https://avatars.discourse-cdn.com/v4/letter/g/50afbb/32.png) [@GorillaMan](https://boards.straightdope.com/u/GorillaMan)\ **Post date:** [March 25, 2004, 11:07am UTC](https://boards.straightdope.com/t/cd-size/236315/4 "2004-03-25T11:07:17Z")
It’s 650MB, assuming you stick to the strict CD specifications. But, as with music where it’s possible to squeeze an extra few minutes on to take it up to 80mins, it’s also possible to stretch the capacity to 700MB. Somebody who knows what they’re talking about can now explain clearly what I’m gabbling about… ---
**Author:** ![TellMeI\_mNotCrazy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tellmei_mnotcrazy/32/3419_2.png) [@TellMeI\_mNotCrazy](https://boards.straightdope.com/u/TellMeI_mNotCrazy)\ **Post date:** [March 25, 2004, 11:41am UTC](https://boards.straightdope.com/t/cd-size/236315/5 "2004-03-25T11:41:05Z")
I agree, 650 (74 min) is the standard. I have a feeling that whoever wrote the quiz might have been mistaking popularity for standard…ness… er, right. Anyway, 700mb CDs are also sold as 80 minute CDs - and therefore sounds more “appropriate” to your average “I wanna put my music on a CD” consumer. ---
**Author:** ![mad\_spoon](https://avatars.discourse-cdn.com/v4/letter/m/fbc32d/32.png) [@mad\_spoon](https://boards.straightdope.com/u/mad_spoon)\ **Post date:** [March 25, 2004, 12:37pm UTC](https://boards.straightdope.com/t/cd-size/236315/6 "2004-03-25T12:37:17Z")
What happened was, new compression techniques made it possible to squeeze most information onto a cd. Nowadays, nearly all cd’s are 700mb, but the “standard” size is 650mb. Cd’s also have a lot of redundancy; if you get a sharp knife and put a scratch radially outwards from the centre of a music cd, it will play fine. But dont come crying to me if it don’t work… ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 25, 2004, 12:55pm UTC](https://boards.straightdope.com/t/cd-size/236315/7 "2004-03-25T12:55:13Z")
Isn’t the 700mb CD just a case of squeezing the the tracks closer together? (I wouldn’t exactly call this a compression technology, which implies some kind of alteration to the actual data). ---
**Author:** ![GorillaMan](https://avatars.discourse-cdn.com/v4/letter/g/50afbb/32.png) [@GorillaMan](https://boards.straightdope.com/u/GorillaMan)\ **Post date:** [March 25, 2004, 12:56pm UTC](https://boards.straightdope.com/t/cd-size/236315/8 "2004-03-25T12:56:14Z")
Aha: > [@](#): > > According to the Red-Book (the standard for CDs), a CD has got a maximum of 74 minutes. > The 80 minute CD-Rs are created by “stretching” the specification: > Every CD has got a track on which the data is written (the same as a record). The distance between the track and the maximum start and end position are defined precisely. Thus there are normally a good 74 minutes available. The distance between the tracks is given with a certain tolerance value. This tolerance value is normally used to balance out inaccuracies in the optics or on the CD. > If the tolerance value is always used right up to its limit, i.e. the track packed as tightly as possible, an 80 minute CD-R is the result. > As there is no “safety reserve” available any more, the smallest deviation on the CD or in the optics of the writer inevitably leads to an error. [http://www.feurio.com/English/faq/faq\_oversize.shtml](http://www.feurio.com/English/faq/faq_oversize.shtml) ---
**Author:** ![Ponster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ponster/32/17081_2.png) [@Ponster](https://boards.straightdope.com/u/Ponster)\ **Post date:** [March 25, 2004, 1:13pm UTC](https://boards.straightdope.com/t/cd-size/236315/9 "2004-03-25T13:13:42Z")
Thx people…makes me feel all warm inside that I’m not as stupid as I had thought 🙂 Well worth $5 ---
**Author:** ![Ponster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ponster/32/17081_2.png) [@Ponster](https://boards.straightdope.com/u/Ponster)\ **Post date:** [March 25, 2004, 1:15pm UTC](https://boards.straightdope.com/t/cd-size/236315/10 "2004-03-25T13:15:46Z")
And welcome to \*\*Gavin G \*\* who is a Charter Member with 1 post ! ---
**Author:** ![Cugel](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cugel/32/1199_2.png) [@Cugel](https://boards.straightdope.com/u/Cugel)\ **Post date:** [March 25, 2004, 1:39pm UTC](https://boards.straightdope.com/t/cd-size/236315/11 "2004-03-25T13:39:05Z")
I’ve got a stack of 100 blank CDs on the desk here, and behind me are 2 x 240 CD wallets - all of them are 700 MB. ---
**Author:** ![sailor](https://avatars.discourse-cdn.com/v4/letter/s/a587f6/32.png) [@sailor](https://boards.straightdope.com/u/sailor)\ **Post date:** [March 25, 2004, 2:17pm UTC](https://boards.straightdope.com/t/cd-size/236315/12 "2004-03-25T14:17:14Z")
> [@mad\_spoon](#): > > What happened was, new compression techniques made it possible to squeeze most information onto a cd. Wrong. Compression has absolutely nothing to do with it. We are talking uncompressed storage capacity. Higher capacity is achieved by having a longer track by placing the successive tracks closer together and/or by taking it to areas of the disc outside the spec. You would have to define “standard”. If you are talking about specs then I believe 650 MB is still the standard. If you are talking popularity then 703 is the most sold but I would argue that may be a “de facto” standard but not the specification standard. ---
**Author:** ![vasyachkin](https://avatars.discourse-cdn.com/v4/letter/v/c5a1d2/32.png) [@vasyachkin](https://boards.straightdope.com/u/vasyachkin)\ **Post date:** [March 25, 2004, 2:36pm UTC](https://boards.straightdope.com/t/cd-size/236315/13 "2004-03-25T14:36:04Z")
well i duno, 700 mb ones play on pretty much all older CD players …