Plain Numbers guidelines
Be consistent
- Always make sure numbers are presented consistently, especially when they are being used for decision making.
- Always keep the same wording, currency, format and units. This makes numbers easier for users to compare.
Put numbers in context
- Always use context or comparisons to help users understand what a number means for them.
For example, instead of “You could get an annuity of £1,000 a month”, say “You could get an annuity of £1,000 a month. For a moderate retirement lifestyle, you need £1,730 a month”.
Use rounded numbers
- Rounding makes numbers easier for users to understand. Where accuracy allows, round numbers to the highest place value that does not make the number misleading. We would not round someone’s balance or contributions.
For example, instead of “Smart estimates the pensions market to be worth £1,256,256,256 by 2024”, use “Smart estimates the pensions market to be worth almost £1.26 billion by 2024”.
- If rounding, always round up where the figure affects users, so as not to create user harm. This is so we make the number simpler for a user, but do not underestimate the amount we guide them to save.
For example, instead of “You should aim for total retirement savings of £415,673” use “You should aim for total retirement savings of £420,000”.
Avoid percentages
- Where possible convert percentages to the specific number they equal. This is because users find percentages harder to understand.
Instead of “Your monthly membership fee is 1.35%”, use “Your monthly membership fee is £2.50”.
- Some screens in the platforms, such as the contributions and investment screens, rely heavily on percentages. We do, for example, show investment returns in terms of money and percentage at the same time.
Use specific dates and times
- Use specific dates and times where possible.
For example, instead of "Your next contribution is due in four weeks", say "Your next contribution is due on 20 April 2025".
Focus on the important numbers
- Try to move or remove numbers that are not relevant to a user’s decision.
For example, when we show two products with different fees, we do not show the breakdowns above the fold.
This is because the total cost is most relevant for a user and should be their focus.
- Aim to move complex calculations below the fold or to the bottom of content. Present the important numbers in simple terms near the top of the page. This is because complex calculations can confuse users and put them off engaging with content.
For example, in a pension calculator, we would show the result at the top. The full calculation and assumptions would be towards the bottom of the tool.
Source: Plain Numbers Research Report
How we write and format numbers
Numbers vs words
Write out the number as a word for one to ten, and use digits for 11 and above. The exception to this is if it would look really weird to write "one". For example, when we're telling people how many messages they have in their inbox, or items on their to-do list – in this case we would use digits ("5 messages in your inbox").
When writing a number range, we use digits. For example, 1 to fifteen. See Number ranges, below.
For numbers over 1 million, style as X.XX million. For numbers over 1 billion, style as X.XX billion.
We use short scale billions, a one followed by nine zeroes.
1st vs first
Use digits for ordinal numbers when referring to days ("the 1st Monday of the month", "the 25th of each month"), but write them out (first, second, third, etc) if it makes more sense to do so in context. For example, "the first thing this statement will show you is..."
Number ranges
Number ranges should always be two digits, with the word 'to' between them ("1 to 15", not "one to 15" or "1-15") as this is the most accessible way to style them. The exception is when a number range appears in a table, in these cases we separate them with a dash.
Numbered steps
Use these when describing a process. Each item in a numbered list should end in a full stop. Use digits to label steps, even if there are less than ten.
If you're referring to a specific step, or telling people how many steps there are as part of a sentence, the normal rule of one to ten as written numbers, and digits for 11 and above applies ("This is a three step process.", "Refer to step five for more details.").
Using different types of numbers
Currencies and money
For currencies, always use decimals. For example, £6.00, £6.47 or £6.10.
Where the amount is less than £1.00, numbers should be styled as 20p (or local equivalent)
Where the amount is £1 million or more, style as £X.XX million. Where the amount is 1 billion or more, style as £X.XX billion.
This applies to all currencies.
Dates
When using a month
Use the format DD Month YYYY. For example, "on 4 January 2019" or "on Friday, 14 January 2019".
The genius component in the platforms and the member app home screen cards use the format D MMM YYYY or DD MMM YYYY where the day has two digits. For example 1 Oct 2022 or 11 Oct 2022.
When using a date range, use 'to' to separate days. For example, "4 to 6 January 2019".
When no month is used
You can use "th/st/nd/rd" when referring to a date alone with no month. For example, "your pension contributions are paid on the 25th of each month".
When using a date range, use "to" instead of a hyphen. For example, "if you opted out between 23rd to 25th of the month".
When summarising information a user has entered in a form
Use the format DD MM YY, for example, 04 01 2019, as this is the format they will have entered the date in the form.
International date formats
Make sure the date is formatted in the most conventional way for that country. For example, when writing for an American audience, the month comes before the date, so "January 4, 2019", "January 4 to 6 2019", or "01-04-2019".
Percentages (%)
We always use the symbol - never write out "percent" or "per cent". Don't put a space between the number and the % symbol.
Times
Use 12 hour time, and style as H.MMam/pm or HH.MMam/pm.
For example, 11.00am or 1.30pm.
Use "midday" and "midnight", unless using them as part of a time range – in which case, use 12.00pm and 12.00am.
If giving a time range (such as the duration of an event), separate with "to" – for example, 2.00pm to 3.00pm.
If writing for an audience that could be international – such as on social media – add the time zone (for example, the webinar is at 11.00am BST).
Unit price
Shown in pence and goes to 2 decimal places. For example, 123.45p.
Units held
Goes to three decimal places. For example, 123.456.