This is more or less a style guide question. I'm curious if anyone is aware of any official style guides that deal with this problem well. I tried to come up with a general approach but I'm curious to see other people's opinions!

Ultimately this is about optimizing two requirements:

  • Readability
  • String size (shorter the better!)

The requirement around the strings being relatively short is due to the fact that the strings could be used on chart labels where space is at a premium.

Here are some of the cases I can see and my suggestion for each:

1. Range with a single unit:
'factor out' the unit, in other words only show the unit once on the outside of the range

ex) 5-6% or $10-15

2. Range with magnitude suffix (K for thousands, M for million, B for billion)
Can't 'factor out' the suffix as above because it leads to ambiguity (for example if we write 5-10k does that mean 5,000-10,000 or 5-10,000?)

ex) 5k-10k or 950k-1M

3. Range with unit AND magnitude suffix:

ex) $5k-10k

ex) 2k-3k% -> pretty messy in this case, the 'k%' almost looks like a new unit! 2,000-3,000% looks much better but takes much more space. I've seen use of 2-3,000% (but that is again also ambiguous)

4. Ranges with negative values:
Things get a bit messy when a dash is used in conjunction with a negative sign

ex) -15% - -8%

ex) -15% to -8% -> much nicer but for visual consistency you'll need to use 'to' everywhere, and it's worse in the case where no negative values exist (5-6% vs. 5 to 6%)

----- Experiment:
I did a quick visual experiment to see all the various cases, the green checkbox marks the style which I find best in each case:

enter image description here


As far as online content goes, the Yahoo! Style Guide has a section dedicated to ranges.

There is also a section detailing the differences between the Yahoo! Style Guide and the Associated Press Stylebook.

You may need to consult the appropriate sections for currency as well as ranges for more detailed examples. I don't want to post extracts from the guides here, as they might change their style over time (thereby possibly associating them with an old style if I post an extract).

As you asked for official style guides, I hope you find them useful.

Edit: Numbers and currency are mostly subject to localisation constraints. Different countries have different preferences to how they display numbers/currency symbols. Depending on your underlying software platform, localisation (internationalisation) support may already be built-in, and you simply need to call the necessary methods to do the conversion for you. This is just something to keep in mind as you refine your proposal.

Edit 2: Lastly, something that has tripped me up in the past is how to properly use abbreviations and their plural forms (if applicable). This is also country-specific, but you can refer to a detailed list of examples at the Yahoo! style guide.

  • I did actually come across the Yahoo style guide but it really doesn't have much in terms of ranges. The link you provided dedicated to ranges simply states that a dash or em hyphen should be used, nothing more. It doesn't talk about any of the issues I raised, such as ranges with units, ranges with k/M/B suffixes, and ranges with negative values. – M.A.X Nov 23 '12 at 18:40
  • Agreed that localization is important, but it's a whole other ball game. With this post I'm wonder how to even deal with ranges for just US-English, never mind other locals! – M.A.X Nov 23 '12 at 18:42

Some places to look:

  • Some bits on ranges are in the Wikipedia Manual of Style: Dates and numbers
  • The Associated Press Style Book has a section on ranges if I recall correctly (don't have access to double check)
  • Ditto for the Chicago Manual of Style

Also - just on this point:

Can't 'factor out' the suffix as above because it leads to ambiguity (for example if we write 5-10k does that mean 5,000-10,000 or 5-10,000?)

In those contexts the suffix is normally read as applying to both numbers when using hyphens. In the style guides I've read you duplicate the suffix if you're using 'to' (e.g. 5k to 10k) but remove it if you abbreviate with a hyphen or n-dash (e.g. 5-10k). I'm pretty sure this is in the http://www.apstylebook.com/ - but I don't have access to it now to double check ;)


My privileges won't let me comment on CJ Franken's answer, but I'd like to add the following.

SI prefixes are prefixes. Use them before the unit. Example: kilometers, km, mg

But you wouldn't say k$337 and you're being so rude to users like you, who go to bed at night thinking about this stuff (me too), if you say $100k. kwhat? M, k, c, all need to go before something. And those units go after each number. You probably know a little physics, and how every measurement has a unit. And the people who don't 100% include units are probably working with electricity or chemistry. They either don't get physics or they're being lazy. And they're wrong.

Edit: Rock on with spacing 2mo - 6yrs. Stick it to the man. Huh!

  • I should have been careful not to use the term 'SI prefix' - you are correct in that official SI units are prefixes. What I'm referring to is the informal use of k, M, and B to represent 1000, 1 million, and 1 billion. This informal convention is widespread and does align with my users' expectations. Now that I think about it, I do wonder about the history of this convention and when it came into widespread adoption, my guess it was an adaptation of the computer science binary representation convention, where 1k represented 1024. – M.A.X Nov 23 '12 at 18:32
  • Yahoo style guide: "If space is an issue, use the following abbreviations: "mil" (million), "bil" (billion), and "K" (thousand)." – M.A.X Nov 23 '12 at 18:38
  • Associated Press Style Book: "Use "M" and "B" in headlines: $1M, $2B." – M.A.X Nov 23 '12 at 18:38
  • Well I'll be darned. Thanks for the style rules. My neutral authority is semantics and your authority is the Yahoo or AP style guidelines. Maybe I'm being too literal. – Tyler Langan Nov 23 '12 at 21:33

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