This resource is an archived version of the Readability Guidelines.
New wiki is at: readabilityguidelines.myxwiki.org
Go to the Numbers page.
Recommendations
Numerals
Use ‘one’ unless you’re talking about a step, a point in a list or another situation where using the numeral makes more sense: ‘in point 1 of the design instructions’, for example. Or this:
You’ll be shown 14 clips that feature everyday road scenes.
There will be:
1 developing hazard in 13 clips
2 developing hazards in the other clip
Write all other numbers in numerals (including 2 to 9) except where it’s part of a common expression like ‘one or two of them’ where numerals would look strange.
If a number starts a sentence, write it out in full (Thirty-four, for example) except where it starts a title or subheading.
For numerals over 999, insert a comma for clarity: 9,000
Use a 0 where there’s no digit before the decimal point.
Avoid using or write out 0 (zero) and 1 (one) where they could cause confusion with the letters "O" and "I" or "l".
Fractions and percentages
Spell out common fractions like one-half.
Use a % sign for percentages: 50%
Use MB preceded by a space for anything over 1 MB: 4 MB not 4096 KB.
Use KB preceded by a space for anything under 1 MB: 569 KB not 0.55 MB.
Keep it as accurate as possible and up to 2 decimal places: 4.03 MB.
Ranges
Use ‘500 to 900’ and not ‘500-900’.
Addresses: use ‘to’ in address ranges: 49 to 53 Cherry Street.
Ages
For most audiences, writing the year followed by the month is most comprehensible. For example: '1 year 6 months' rather than '18 months', 'a year and a half' or '1.5 years'.
Below 1 year, use months e.g. 6 months old.
Typography
Use a clear and familiar typography. 1 and I can look the same depending on the typeface.
Data
Be specific and again, consider the context.
20% of 10 people is very different to 20% of 100.
Usability evidence
'The innate mind: Structure and Contents Part III > Number and natural language', 2005
'Formatting the value of a quantity', 2006
'Show numbers as numerals when writing for online readers', 2007
GOV.UK Style guide A to Z, UK Government, 2016
GOV.UK Content principles, UK Government, 2016
Some potential topics for the Numbers section. Any more suggestions?
Looks good :)
Taking the first one: Numerals vs words. Do we think there enough evidence to say this is ok and we all agree?
Yes and to chip in - non english speakers (majority) can understand 10,000 over Ten thousand.
I have often wondered where this rule comes from? Historial uptake from print style guides like oxford guide to style / editors and others?? we do digital and the history of many style guides is wrapped up in print not digital. Is it ok to start a sentence with a number in 2018? Be keen to understand more the reasons why not.
Yes, use numerals. There is no scientific basis for not starting a sentence with a numeral, just a matter of prefered style. I avoid it by rewriting the sentence.
I am not in the habit of using fractions, but I would think that it should still be expressed a a figure, not a phrase.
When a series of amounts is provided, all should be in the same format. By this I mean do not compare different types, as in: 1 in 5 are this, but 35 % are that, while a majority are different.
Use figures—
With numbers nine and below grouped for comparison in the same sentence or paragraph with numbers 10 and above—
3 of 21 students; 9th and 12th grades
With numbers preceding symbols and abbreviations—8ºC, 4 MB, 5-mg dose
With names of parts of books, series, tables, etc.—chapter 2, volume 7, row 9, grade 3
With percentages—1 percent; mixed fractions—2½ years; decimals—1.3 times; and ratios—2 to 1
With sums of money—$5.25, $7 million
With military units—1st Army, 7th Fleet
Inclusive numbers (use the en dash; see 4.14.4 for how to type dashes)
103–210 141–48 107–8
1960–64 1903–5 1882–1902 1900–1920
"Keep it as accurate as possible and up to 2 decimal places: 4.03 MB."
I'd add something along the lines of: Unless it is appropriate to be more accurate (e.g. in referencing something scientific/medical, where accurate measurements are important).
Should dates come into this section as well? Date formatting can really vary, especially in product copy.
Or should time and date have a separate section? Is there enough to go in there?