Dates
General rules
Use the ISO 8601 date and time format standards when backend localization is not possible.
Add tooltips or in-line text to support users and clarify which format is being used.
Avoid adding unnecessary punctuation to abbreviated dates.
Dates
Write out full dates using commas to separate elements within longer texts and paragraphs.
Write out dates with the abbreviated form using dashes (hyphens) instead of slashes for better readability.
Write dates in tables using abbreviated months to avoid confusion and the need for further tooltips or explanation.
Avoid using “st” (as in 1st) or “th” (as in 5th) for a cleaner user interface.
Days
Start all days with a capital letter. Use three-letter abbreviations without punctuation when there isn’t enough space.
Weeks
Avoid calendar weeks (CW) whenever possible as these are very specific to certain regions.
Months
Start all months with a capital letter. Use abbreviations without punctuation when there isn’t enough space.
Years
Use the four-digit format and never abbreviate in industrial applications.
Decades
Use plural -s when talking about decades.
Centuries
Use “th” and “nd” to reference centuries with ordinal numbers (sequencing) without using superscript.