Writing the 30th date in English requires balancing professional standards, regional norms, and document context. Whether you're drafting a business contract, sending an international email, or publishing a news report, formatting the number thirty correctly prevents confusion and maintains your credibility.
Major style manuals, including the Chicago Manual of Style, point out that date formatting changes depending on your audience. This guide breaks down exact rules, regional differences, ordinal suffixes, and common errors to help you write the 30th date accurately every time.
Understanding Ordinal Suffixes for the 30th
When writing dates with words or ordinals, the number thirty takes the suffix -th.
- Numeric ordinal: 30th
- Spelled out: thirtieth
You should avoid incorrect ordinal forms like 30rd or 30st. While numbers ending in 1, 2, and 3 use -st, -nd, and -rd (1st, 2nd, 3rd), the number 30 follows the standard pattern for numbers ending in zero, which take -th (30th, 40th, 50th).
Standard Professional Formats
Different industries rely on distinct layout conventions. Here are the three primary ways to write the 30th in professional English.
International and European Style (Day-Month-Year)
This format places the day first, followed by the month and year, without ordinal suffixes or commas. It is standard across the United Kingdom, Europe, and most Commonwealth nations.
- 30 March 2026
- 30 Mar 2026
American Style (Month-Day-Year)
In American English, the month comes first, followed by the day and year. A comma is required after the day when the year is included to separate the day from the year.
- March 30, 2026
- Mar. 30, 2026
ISO 8601 Standard (Year-Month-Day)
For technical writing, databases, invoices, and software systems, the international standard ISO 8601 dictates starting with the four-digit year, followed by the month and day. This eliminates all regional ambiguity.
- 2026-03-30
Figures vs. Words: When to Spell It Out
Choosing between numerals and spelled-out words depends heavily on the formality of your text.
Business and Technical Writing
In business emails, reports, and data sheets, numerals are preferred because they consume less space and offer instant readability.
- Example: The project deadline is 30 March 2026.
Formal Legal and Narrative Prose
In formal legal agreements, certificates, or ceremonial texts, spelling out the date adds solemnity and prevents document tampering.
- Example: This agreement is entered into on the thirtieth day of March, in the year two thousand twenty-six.
Punctuation Rules You Need to Know
Incorrect punctuation is the most frequent error writers make with dates. Follow these rules to keep your work clean:
- Don't use ordinal suffixes with full numeric dates. Write March 30, 2026, not March 30th, 2026. The suffix is redundant when the year and month are present.
- Place commas correctly in American English. If you write out a full sentence containing an American date, a comma must follow the year as well.
- Correct: On March 30, 2026, the board approved the budget.
- Omit commas in British short dates. When writing in UK format, commas are unnecessary.
- Correct: On 30 March 2026, the board approved the budget.
Frequently Asked Questions
Should I write 30th or 30 in a sentence?
If you're using the month and year, use the cardinal number (March 30). If the month is omitted or you are referencing a day independently in a narrative, use the ordinal form (We met on the 30th).
Is a leading zero required for single-digit months?
In numeric-only formats like 30/03/2026, adding a leading zero to the month (03) is recommended to maintain column alignment and system compatibility.
How do I write the 30th in military or aviation English?
Military and aviation logs typically place the day before the month in all-caps abbreviation without punctuation, such as 30 MAR 2026.
Can I abbreviate March to Mar.?
Yes, abbreviating months to their first three letters is standard in tight spaces like tables, charts, and schedules. Always include a period after the abbreviation in American English, though it's often omitted in modern British style.
