I know that "processor architecture" can be used to refer to whether the processor is 32-bit or 64-bit (or something else), but what word can be used for the operating system? Note that it's not necessarily the same as the processor architecture, e.g. I can install a 32-bit OS on a 64-bit machine.

Also, this is for a business document for non-technical people, so I'd like to avoid an overly technical terminology.

  • But for the edit, the q. would've been entirely 'off-topic' on ELU.
    – Kris
    Commented Apr 15, 2012 at 8:50
  • I can install a 32-bit OS on a 64-bit machine. - there are only a limited number of processor architectures for which this is true, and this is in the case when the physical machine has support for an earlier processor architecture.
    – Random832
    Commented Apr 15, 2012 at 19:25
  • Basically you're talking about "compatible architecture".
    – Hot Licks
    Commented Mar 26, 2017 at 22:03

6 Answers 6


I suggest bitness, in the sense of "The architecture of a computer system in terms of how many bits compose the basic values it can deal with". (Logitech uses it, Microsoft uses it to specify operating-system bitness, et al.)

  • I have heard bit depth, which is close enough to this to not warrant its own answer. Commented Apr 21, 2012 at 14:50
  • 4
    I've only heard bit depth used in the context of images.
    – Pitarou
    Commented May 1, 2012 at 4:11
  • I have never ever heard the term "bitness". But then I've only been in the computer biz for 40 years.
    – Hot Licks
    Commented Mar 26, 2017 at 22:04

Word size (e.g. here's a table of word sizes in Wikipedia) or word length.

  • 6
    -1: I don't like to do that, but the OP is specifically asking for a word to talk about the "bitness" of the OS not the hardware. The word size table you point to shows hardware word sizes. This is because in computing 'word' is used to refer to the natural memory access size used by a processor. The word size of the processor remains the same regardless of the "bitness" of the OS running on it.
    – Jim
    Commented Apr 15, 2012 at 22:45
  • 1
    +1, as this is about the best answer possible. However, Word size, Register Size, Address size, and internal bus size can all be different things. For example, for M68000 the first was OS dependent, and the others were 32, 24, and 16 respectively.
    – T.E.D.
    Commented Apr 16, 2012 at 17:57

runs on

A phrase like "runs on 64-bit (32-bit) computers" would make more sense to a lay user.

An alternative, if applicable could be optimized for.

A single word, least a noun, would not suit your audience's reading level.


What about OS architecture or software architecture?

EDIT: per Wikipedia's comparison of CPU architectures, props to zpletan:

Computer architectures are often described as n-bit architectures. Today n is often 8, 16, 32, or 64, but other sizes have been used.

  • I was thinking about that, too, but it might be ambiguous (can also refer to whether the OS architecture is NT, 9x, etc)
    – Fitri
    Commented Apr 15, 2012 at 5:51
  • @Fitri, it is no more ambiguous than processor architecture, which could either refer to 16-/32-/64-bit or to ARM/i386/etc.
    – zpletan
    Commented Apr 15, 2012 at 12:24
  • Per Wikipedia (Comparison of CPU architectures), "Computer architectures are often described as n-bit architectures." I might on that basis suggest prefixing n-bit to this answer if you want to be more explicit.
    – zpletan
    Commented Apr 15, 2012 at 12:29
  • The reason I don not like OS architecture or software architecture for this is that OS architecture is the term used to refer to the basic design paradigm used for the OS such as: microkernel, monolithic, hybrid, etc. And software architecture is described in IEEE-1471 and is used to refer to the general field of study focusing on the fundamental organization of a system as embodied by its components. So neither is an appropriate term to refer to "bitness"
    – Jim
    Commented Apr 15, 2012 at 17:56

I think I'd have to pick something like:

OS address-size or address-width

or maybe

OS pointer-size/width

  • That answer would suit very well, but how many non-technical people will get wiser with those words?
    – MarioDS
    Commented Apr 15, 2012 at 7:19
  • @MarioDeSchaepmeester to be fair the answer was posted before I edited to mention that this is for non-technical people. But you are right, I don't think this works well for non-technical people
    – Fitri
    Commented Apr 15, 2012 at 7:34
  • 4
    IF you are talking to non-technical people you could just refer to the word-size or natural word-size of the OS. The thing is, you are dealing with a technical subject you'll need a technical description. Non-technical people will have heard of 32-bit and 64-bit as simply names but they won't really know what it means. So you say something like "The OS Memory Model, e.g. 32-bit or 64-bit" and they'll get it.
    – Jim
    Commented Apr 15, 2012 at 7:50
  • +1 for Jim's comment. As an example of how complex it can be have a look at the history of IBM's XA en.wikipedia.org/wiki/IBM_System/370 warning - contains more than 100% of your RDA of WTFs.
    – Wudang
    Commented Apr 15, 2012 at 11:33
  • Address space? Does that work?
    – Brad
    Commented Apr 30, 2012 at 18:47

If you mean x86 versus x86_64, it's "instruction set" or "architecture". The fact that one is 32-bit and the other is 64-bit is just one of the differences between these two architectures.

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