Numbers

From dates to page numbers to percentages; how to use numbers correctly.

Writing numbers

Write all numbers 10 and over as numerals, up to 999,999.

Write numbers zero to nine as words unless they are technical or precise, such as dates, figure or table titles, or relate directly to the statistics being presented.

Where a range crosses the 10 boundary, use numerals.

Write out rankings first to ninth, then use numerals. Do not use superscript for “st”, “nd”, “rd” and “th”.

A sequence of numbers should use the same format for both, which should follow the higher number.

Do not use abbreviations of “numbers”, such as “no” or “nos”. They can be read incorrectly.

Use commas to separate thousands in numbers of four digits or more, and never spaces (except when writing years – these should have no punctuation).

Avoid writing sets of numbers together.

Use a 0 where there is no digit before the decimal point in a number.

Do not start a sentence with a numeral. Rearrange the sentence accordingly.

Do not use a hyphen to indicate a range of numbers, separate with “to”.

Number rounding

Rounding numbers can make them easier to read and compare, although this must be balanced against the loss of precision.

The level of rounding you use (for example, one decimal place or two significant figures) should be effective, and chosen according to the intended use. It should also be consistent throughout your piece of writing.

For more detail about intended users, go to Number rounding in the Data visualisation section.

For more information about presenting tables and graphs (including rounding on page 7), see the Government Statistical Service’s Good Practice Team guidance.

Generalised numbers

Write out generalised numbers.

Millions and billions

Write out and use lower case.

Do not use “0.xx million” for numbers less than 1 million, unless part of a sequence of numbers

Page numbers

Use the fewest digits possible while remaining clear. Separate them with “to”.

Plus and minus

In text, when referring to positive and negative numbers, write out “positive” and “negative” in full.

In a dataset, use the symbols with no space between them and the number.

Fractions

Write out and hyphenate fractions.

Avoid using too many fractions as it can be difficult to compare several together.

Also avoid using large denominators.

Write out decimal fractions as numerals. Use the same number format for a sequence of fractions and decimals.

Percentages

Use the percentage symbol with no space between it and the number.

Always write “percentage” and never %age.

Use the same number of decimal places for a sequence of decimal numbers.

A percentage point is the difference between percentages. A value of 10% falling by 1 percentage point becomes 9% (10% has 10 percentage points). A fall of 1% would result in a value of 9.9%

Dates

Use the format “[Date] [Month] [Year]” (depending on what information you have) written out with no commas. If the day of the week is relevant, then put it before the date. Do not include “st”, “nd”, “rd” and “th” after the date.

Write out months in full. If space is limited (such as in a table) use the shortened version with no punctuation, but not for June and July. Do not use shortened versions of months in titles.

Date spans

Use the format “[date] to [date]” to state the reference period for your data.

If using months within the same year, only write the year after the subsequent month.

If the period spans years, add the relevant year after each month.

For a period between two dates, use the format “between [date] and [date]”.

Do not use hyphens, dashes or forward slashes to indicate date spans. It is quicker to read “to”, and special characters can cause problems for screen readers.

Decades

Decades should only have an apostrophe when they are a possessive, not a contraction.

Centuries

Use ordinal numbers when referring to a particular century.

Quarters

Define the quarter, the months covered, and the year. Explain which months are included in the quarter in the first instance of each section, and only include the quarter and year in every subsequent instance. Abbreviate the months to three or four characters. In titles write the months in full and avoid using quarters.

Financial, tax and academic years

For financial years, write “financial year ending” and the abbreviation “FYE” in brackets, followed by the year for the first time you use it in each section. After that, just use the abbreviation and the year. The full phrase should be written out again for the first mention in each section.

If a date span covers this period but you do not want to refer to the financial year, either write “year ending March 2018” or “April 2017 to March 2018” depending on what you think will meet your users’ needs.

If your data source uses another recognised date span such as the academic or tax year, write this in each instance without using hyphens, dashes or slashes.

Include a definition of the months included in a non-calendar date span near its first reference in the text so that all users can understand the dates you are referring to. This will only need to be defined in the first instance of your bulletin or article.

Change in data over time

If you need to show a change in the data between two date spans, include the month and year in brackets after each figure. Use the format “from [amount] (month year) to [amount] (month year)”.

Reference across different time periods and countries

When reporting on different geographic areas that use data from different date spans, state the month and year of the data collection after each area. Use the appropriate format for the date range, and place the information in brackets.

Time

Do not use the 24-hour clock. Do not insert spaces between the number and the letters, and do not use any punctuation except as shown.

Use the same number format for time spans.

Ages

Use the format “aged [age] years”

Use the format “aged [age] to [age] years”.

Include the months or weeks for ages under a year.

If you refer to ages as “[age]-year-old”, include the hyphens.

Write decades as an age as numerals.

Limits for age restrictions should use “aged [age] years and over” or “aged under [age] years”. Do not use the plus sign.

Money

Use the major currency unit before the amount. Do not use decimals unless using smaller units.

In a sequence of numbers, use the same number of decimal places, even if every number does not have a smaller unit.

Do not use “0.xx million” for amounts less than 1 million, unless in a sequence of numbers.

Write out the smaller unit in full.

Currency should use lower case.

Write out currency as “British pounds”, or “American dollars”.

Measurements and units

Use metric units of measurement, except in specific cases where imperial units are still used as standard.

Write out measurements at first mention, then abbreviate. If it is only mentioned once, do not abbreviate.

Abbreviations should not have full stops and are always singular. Use a space between the number and the abbreviation, except with one-letter abbreviations.

Write out “miles” and “metres” in full.