Summary
Dates and times are high-precision data. In academic writing you should prefer explicit, unambiguous formats over vague phrases such as “recently” or “lately.” Use a consistent date style (e.g., British “11 August 2014” or American “August 11, 2014”), avoid all-numeral forms unless you standardise them (preferably ISO 8601, YYYY-MM-DD), and write centuries, decades, and eras (BC/BCE, AD/CE, BP) consistently and in their correct positions.
For time, clarity beats custom. Whole hours and informal references can be written in words, but exact measures take numerals (“a 30-minute trial”). Prefer “noon” and “midnight” to “12 a.m./p.m.” Use the 24-hour clock (e.g., 17.00 or 17:00) to remove ambiguity, and specify time zones and UTC offsets for events, especially when daylight saving may apply.
Bottom line: pick one defensible standard; announce it once; apply it everywhere. Use en dashes for ranges (2010–2014), hyphenate adjectival compounds (“twenty-first-century study”), and provide cross-checks in tables/figures. Consistent, precise timekeeping increases readability, reproducibility, and cross-disciplinary interoperability.
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Dates & Times in Academic Writing: Precise, Consistent, and Unambiguous
Dates and times may look like “mere formatting,” but they carry methodological weight. Ambiguous timestamps blur timelines, inflate error bars, and mislead cross-border readers. This guide consolidates best practice for writing dates, periods, eras, and clock time in scholarly prose, with British vs American variants, ISO standards, and layout tips for tables, notes, and figures.
1) Specific beats vague: favour explicit dates
Replace “recently” and “in the last few years” with exact spans or dates—“between 2019 and 2021,” “on 11 August 2014,” “from 3 May to 7 June 2023.” Precision helps reviewers verify chronology and readers reproduce procedures.
2) Choose a date format and stick to it
| Context | Preferred form | Example | Notes |
|---|---|---|---|
| British English (running prose) | Day Month Year | 11 August 2014 | No commas; months capitalised |
| American English (running prose) | Month Day, Year | August 11, 2014 | Comma after day; month capitalised |
| All-numeral, international | ISO 8601 (YYYY-MM-DD) | 2014-08-11 | Hyphens or thin spaces; ideal in technical contexts, filenames, datasets |
| Ordinal day alone | 11th (or the 11th) | “The trial took place on the 11th.” | Ordinals typically avoided when month/year included |
11/08/14 (DD/MM/YY vs MM/DD/YY). If you must use numerals, declare your convention and apply it consistently; better, use ISO 8601.3) Punctuation and separators
- British prose: no comma—11 August 2014.
- American prose: comma after day—August 11, 2014.
- Technical writing: ISO 8601 uses hyphens (2025-11-11); some disciplines permit en dashes (2025–11–11) to match typographic style.
- Historic/philological contexts: you may encounter lowercase Roman numerals for months in archival references (11.viii.14); explain the scheme if you adopt it.
4) Ranges and spans: use en dashes and reduce repetition
- Years: 2010–2014 (en dash; no spaces).
- Full dates: 11–13 August 2014 (share month and year once).
- Cross-month: 28 August–3 September 2014.
- Spelled-out months (US): August 28–September 3, 2014.
5) Decades, centuries, and adjectives
- Decades: the 1960s or the sixties (no apostrophe in 1960s; an apostrophe only indicates omitted numerals: the ’60s).
- Centuries (prose): write out—the twenty-first century, the twelfth century.
- Centuries (notes/tables): abbreviate if needed—12th c. or 12th cent. (choose one form and use it consistently).
- Adjectival form: hyphenate—a twenty-first-century vehicle, a twelfth-century manuscript.
6) Eras and archaeological/chronological systems
| Marker | Placement | Example | Notes |
|---|---|---|---|
| AD (Anno Domini) | Before numerals | AD 1131 | In prose “AD” often omitted unless contrast required |
| BC (Before Christ) | After numerals | 310 BC; 10,000 BC | Use comma in 5+ digit BC years (and BP) for readability |
| CE/BCE (Common Era) | After numerals | 679 CE; 156 BCE | Use consistently if avoiding religious terms |
| BP (Before Present) | After numerals | 12,000 BP | “Present” is conventionally AD 1950; add context if mixing scales |
7) Times in prose: when to use words vs numerals
- Durations in running text: use words for approximate periods and small round numbers—“the test lasted seven weeks,” “after two hours.”
- Exact measures and compounds: use numerals—“a 30-minute trial,” “a 15-second exposure.”
- Whole hours: words acceptable—“eight o’clock,” “half past three,” “a quarter to seven.” Hyphens not needed in these idioms.
- Do not double-mark: choose either o’clock or a.m./p.m., not both (write five o’clock in the morning or 5 a.m.).
8) 12-hour vs 24-hour clock
To prevent ambiguity, especially in schedules, methods, and time-series, prefer the 24-hour clock and avoid “12 a.m./p.m.”
| System | Form | Examples | Notes |
|---|---|---|---|
| 12-hour | H.MM a.m./p.m. (or H:MM) | 10.45 a.m.; 6:13 p.m. | Use periods in “a.m./p.m.” in British; “A.M./P.M.” common in American styles |
| 24-hour | HH.MM (or HH:MM) | 12.00 (noon); 17.00; 24.00 (midnight) | Prefer full stop in British typography; colon common in North America |
9) Time zones and UTC offsets
For data collection, online experiments, server logs, and multi-site studies, append a time zone or UTC offset.
- Offset form: 2025-11-11 14:00 UTC+00:00 (or 14:00Z for UTC exactly).
- Zone abbreviations: write the region name (e.g., Europe/London) rather than ambiguous abbreviations like BST or EST that change with daylight saving.
- Daylight saving: for events near transitions, specify both local time and UTC—“02:30 local (01:30 UTC)”—and the date of the change.
10) Minutes, seconds, and sub-second notation
- Use SI style in technical descriptions—30 s, 5 min, 2 h, 3 d—with spaces between numerals and units.
- For precise timestamps, ISO 8601 allows seconds and fractions—2025-11-11T14:06:32.415Z.
- In prose, keep readability: “after 30 seconds,” “within five minutes.”
11) Tables, figures, and captions: design for clarity
- Column headers: include units—Time (24-h), Date (ISO 8601).
- Captions: restate the convention—“Dates are YYYY-MM-DD; times are local (Europe/London) 24-hour clock.”
- Sorting: ISO dates sort naturally as strings; avoid “11 Aug 14” in CSV/TSV where sorting must be lexical.
12) British vs American conventions: quick reference
| Issue | British English | American English |
|---|---|---|
| Date order | 11 August 2014 | August 11, 2014 |
| Ordinal with date | Ordinals only when day stands alone (the 11th) | Similar; ordinals in prose more common informally |
| Time separator | Full stop often (10.45) | Colon standard (10:45) |
| a.m./p.m. | Lowercase with periods (a.m./p.m.) | Often uppercase with periods (A.M./P.M.) |
13) Special cases and edge scenarios
- Seasons: lowercase in British style—spring 2024—unless part of a formal title; some American house styles capitalise—follow your journal.
- Fiscal/academic years: use an en dash—FY 2023–24, academic year 2024–25 (do not mix hyphen and slash).
- Circa and uncertainty: c. 1150 or ca. 1150 (choose one); specify ranges when known—1150–1160.
- Calendars: if using non-Gregorian dates (e.g., Hijri, Hebrew), provide a parenthetical Gregorian conversion the first time.
- Old Style/New Style (Julian/Gregorian): for historical work spanning the 16th–18th centuries, indicate “OS/NS” where relevant.
14) Grammar and typography notes
- Do not place a comma between month and year alone in American English: write August 2014, not August, 2014.
- Use a thin space or no space around en dashes for ranges depending on house style—be consistent.
- Avoid superscripting ordinal suffixes in formal prose (11th, not 11th), unless your journal mandates it.
15) Recommended house statement (drop into your methods section)
“Dates are reported in ISO 8601 (YYYY-MM-DD). Times use the 24-hour clock and include time zone where relevant. Eras follow CE/BCE notation. Ranges use en dashes (e.g., 2010–2014).”
16) Worked examples
British prose: “Participants attended on 11 August 2014 at 10.45 (Europe/London). Follow-up visits occurred on 28 August–3 September 2014.”
American prose: “Participants attended on August 11, 2014 at 10:45 a.m. (America/New_York). Follow-up visits occurred August 28–September 3, 2014.”
Technical log: 2014-08-11T10:45:00Z → 2014-08-11T17:00:00+07:00 (converted for local site).
Archaeology: “Charcoal layer dated to 310 BC (95% HD interval 340–280 BC; also reported as 2,300 BP).”
17) Common mistakes (and how to fix them)
- Ambiguous numerals: 11/08/14. Fix: 2014-08-11 or 11 August 2014.
- Misplaced era label: AD 2014 is fine; 2014 AD is less common. For BCE/CE, label after numerals—156 BCE.
- Apostrophe decade: 1960’s. Fix: 1960s or ’60s.
- Hyphen for range: 2010-2014 in polished prose. Fix: en dash—2010–2014.
- “12 a.m./p.m.” ambiguity: Fix: noon and midnight or 12.00 and 24.00 (24-hour clock).
- Zone ambiguity: “6 p.m. PST” in July. Fix: “18:00 America/Los_Angeles (UTC−07:00)”.
18) A short checklist before submission
- One date format chosen and applied throughout (announce it once).
- Ranges use en dashes; shared elements not repeated unnecessarily.
- Decades and centuries styled consistently; adjectival centuries hyphenated.
- Eras (AD/BC or CE/BCE) used consistently and positioned correctly; BP definitions clear.
- Times expressed unambiguously; “noon”/“midnight” preferred over 12 a.m./p.m.
- 24-hour clock used for schedules and methods; minutes separated by full stop (British) or colon (American) consistently.
- Time zones/UTC offsets given where cross-regional interpretation matters; DST transitions considered.
- Tables and figures label date/time conventions; CSV/TSV use ISO 8601 for sorting.
Conclusion
Good timekeeping is good scholarship. When your dates and times are precise, consistent, and typographically correct, you remove friction for readers, indexers, and future analysts. Pick a defensible convention—British, American, or ISO—state it once, and apply it everywhere. Your prose will read more cleanly, and your findings will be easier to verify, replicate, and cite.
