Fractions in Writing
Choose the representation that matches the reader’s precision needs and the document’s style. A phrase such as “about two-thirds” works well for an approximate share in prose; a value such as “0.667” communicates a different level of numerical precision. Keep the choice consistent within comparable material.
In general prose, common fractions can often be written in words when exact precision is not the point; in technical, scientific, measurement, comparison, table, or data contexts, numerals or decimals are often clearer. The governing house style controls the exact convention.
Key details
Further guidance
Consistency
Once the document’s style and context establish a treatment, keep comparable fractional values consistent unless a precision difference is meaningful.
Context
Use the conventions required for measurements, tables, equations, scientific material, or specialist content instead of applying a general-prose spelling rule mechanically.
Precision Check
Ask whether the reader needs an approximate share or an exact numeric value. Use words naturally for approximate general prose and numerals/decimals when precise comparison or calculation matters.
Worked Example
“About two-thirds of respondents agreed” signals an approximate share; “66.7% of respondents agreed” communicates a more exact reported value.
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.
- Fractions and decimals (opens in a new tab)Australian Government Style Manual · Distinguishes fractions from decimals by communicative precision and gives current conventions for representing fractional values in prose.
- Choosing numerals or words — Style Manual (opens in a new tab)Australian Government Style Manual · General government-writing preference for readable large-number wording