Ratios in Writing
This guide covers representation of ratios in writing, not how to calculate them. Formatting choices should make the relationship easy to read and should yield to domain-specific or publisher conventions when those differ.
When presenting a mathematical ratio in general prose, a common style is numerals separated by a colon with no spaces, such as 3:1. Follow the governing publisher or accessibility requirements, and use words when a symbolic ratio would be unclear to the audience.
Key details
Important caveats
Boundary
Do not use this guide to calculate ratios, and do not override domain-specific notation or existing business-metric guides.
Further guidance
Accessibility
Spell out or explain the relationship when the symbolic form would be unclear for the audience or accessibility context.
Decision Path
If the task is to display an already-known ratio, use the governing style’s numeric convention; in general prose, a compact colon form such as 3:1 is common.
Worked Example
“The mixture uses a 3:1 ratio of water to concentrate” states the relationship in compact form and names what each side represents.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- Mathematical relationships (opens in a new tab)Australian Government Style Manual · The Style Manual says ratios are written with a colon and no space around the colon and advises plain-language/accessibility choices for mathematical relationships in general content.
- Colons (opens in a new tab)Australian Government Style Manual · The Style Manual gives writing examples such as 50:50 and 7.5:1 and explicitly treats the colon as the punctuation mark used for mathematical ratios.