How to Write Dates in English (British, American, ISO Styles)

Learn how to write dates correctly in English. Compare British, American, and ISO formats, and see how to use them in formal and informal writing.

Writing dates correctly in English can be confusing. Different countries use different formats, and rules change depending on the situation.

This guide will show you exactly how to write dates correctly in English. You’ll learn the British, American, and international formats, how to write dates in formal and informal situations, how to pronounce dates, and the most common mistakes to avoid.

The Main Date Orders: British, American, and ISO

When you write dates in English, the order of the day, month, and year changes depending on where you are. British and American English follow different rules, while the ISO format is used internationally for clarity. Understanding these three main styles helps you write dates correctly for any audience.

Format	Order	Example	Notes
British	Day → Month → Year	15 October 2025	Common in the U.K., Australia, Commonwealth nations
American	Month → Day → Year	October 15, 2025	Standard in the U.S.
ISO / International	Year → Month → Day	2025-10-15	Used in tech, data, international settings

The ISO format (YYYY-MM-DD) is especially useful when you write for global or technical audiences. It’s unambiguous and sorts chronologically. It’s recommended to use it in files, databases, and international communication.

The Two Main Styles: British and American

English-speaking countries use two main date formats, British and American. Let’s look at how they differ.

British English Date Format

In British English, you write the day first, then the month, then the year.

Examples:

• 15 October 2025
• 15th October, 2025
• Monday, 15 October 2025

This format is common in the UK, Ireland, Australia, and other Commonwealth countries.

When using only numbers, the format is:
DD/MM/YYYY → 15/10/2025

American English Date Format

In American English, the month comes first, then the day, then the year.

Examples:

• October 15, 2025
• Oct. 15, 2025
• Monday, October 15, 2025

When writing in numbers, the format is:
MM/DD/YYYY → 10/15/2025

You’ll also notice that Americans always include a comma after the day when the year follows.

Why Writing Dates Correctly Matters

Dates appear everywhere in emails, letters, invitations, essays, and even job applications. Using the wrong format can confuse your reader or even cause serious misunderstandings.

Clear date formatting isn’t just about grammar; it affects contracts, travel bookings, and even legal documents. A single mix-up can cost time and money.

For example, 05/11/2025 means May 11 in the United States but 11 May in the United Kingdom. The difference could change the meaning of an appointment or deadline entirely.

Knowing how to write dates correctly helps you communicate clearly and professionally.

Ordinal Numbers vs Cardinal Numbers in Dates

Ordinal numbers (1st, 2nd, 3rd, 4th) show position or order. In writing dates, using them is optional, and sometimes discouraged, depending on style.

• In formal writing, most style guides prefer cardinal numbers (1, 2, 3, 4) in dates. For example: “July 27” instead of “July 27th.”
• In informal or conversational text, ordinal numbers (27th, 3rd) add a natural feel.

So:

• Formal: 27 July 2025
• Informal: 27th July 2025 or July 27th, 2025

Be consistent in your document, don’t switch between “27 July” and “27th July” for no reason.

Writing Dates in Words

You can write dates in words or numbers depending on the formality.

Full Written Dates

Use capital letters for months, and decide whether you want to include “the” and “of.”

British Examples:

• 15 October 2025
• the 15th of October, 2025

American Examples:

• October 15, 2025
• October 15th, 2025

In formal writing, drop “the” and “of” for a cleaner look.

Correct (formal): 15 October 2025
Less formal: the 15th of October, 2025

Using Ordinal Numbers

Ordinal numbers (1st, 2nd, 3rd, 4th) show sequence but are optional when writing dates.

Formal: 2 January 2025
Informal: 2nd January 2025

Both are correct. The formal version is cleaner and preferred in professional or academic writing.

Writing Dates in Numbers

If you use numbers, be clear about the format. Different countries use different systems:

• British English: DD/MM/YYYY → 15/10/2025
• American English: MM/DD/YYYY → 10/15/2025
• International (ISO): YYYY-MM-DD → 2025-10-15

The ISO format is useful for business and international communication because it avoids confusion.

Avoid writing dates in numbers only when possible, especially in formal writing.

Tips for numeric dates:

• Use four-digit years (2025, not ’25) when clarity matters
• Use leading zeros for single-digit days and months (e.g. 05/08/2025) when your format is fixed-width
• Choose separators clearly: slash (/), dash (–), or period (.), but don’t mix them in one document
• Avoid ordinal suffixes (th, st) with numbers-only dates

Numeric-only dates are ideal for charts, spreadsheets, digital interfaces, or compact displays. In narrative text, spell out at least the month name to avoid ambiguity.

Writing Dates in Formal Contexts

In formal writing like reports, essays, and letters, write dates in full words.

• Spell out the month fully
• Use cardinal numbers for days
• Use four-digit years
• Use full date format, not numeric-only
• Add commas in American style

Examples:

• 15 October 2025 (British)
• October 15, 2025 (American)

If including a day of the week:

• British: Monday 15 October 2025
• American: Monday, October 15, 2025

Don’t abbreviate months, and avoid ordinal numbers. This style looks professional and polished.

Notice in U.S. format, you place a comma after the day of the week and after the day. Example: Friday, December 21, 2012, was unforgettable.

In British style, commas are less common: Friday 21 December 2012 was unforgettable.

Writing Dates in Informal Contexts

In casual writing in informal emails, texts, and social media, you have more flexibility:

• Use short numeric forms (e.g. 10/15/25 or 15/10/25)
• Use abbreviated months (Oct, Sept, Mar)
• You can include ordinal numbers (e.g. Oct. 15th)
• Omitting the year is acceptable if context makes it clear

Examples:

• 10/15/25 (American)
• 15/10/25 (British)
• Oct. 15 (informal)

Just make sure your audience understands which format you’re using.

Writing Dates With Days of the Week

Including the day of the week makes your message clearer.

Examples:

• Monday, 15 October 2025 (British)
• Monday, October 15, 2025 (American)

In American English, always place a comma after the day of the week.

Example: Friday, December 21, 2012, was a memorable day.

In British English, commas are usually omitted.

Example: Friday 21 December 2012 was a memorable day.

Writing the Year

Years should be written as numbers, except at the beginning of a sentence.

Correct:

• The year 1929 changed history.
• Two thousand twenty-five will be exciting.

Avoid starting a sentence with a number. Write the year in words instead.

You can also write years in different ways depending on style:

• British: Two thousand and sixteen
• American: Two thousand sixteen

Both are correct. Use the one that matches your audience.

Writing Centuries and Decades

When writing centuries, remember: they are plurals, not possessives.

Centuries

Centuries are plurals, not possessives:

• Correct: the 1800s, the nineteenth century
• Wrong: the 1800’s

When writing “century” in text, use lowercase unless part of a proper noun: the 19th century.

Decades

Decades should use an apostrophe only to show missing numbers, not for plurals or possesion:

• Correct: the ’90s, the 1990s, the nineties
• Wrong: the 90’s

An apostrophe before the two-digit number indicates the century part is omitted.
Example: ’80s = 1980s.

Always use a straight apostrophe (’) before the decade number.

Writing Dates for International Readers

If you write for an international audience, use the ISO format (YYYY-MM-DD).

Example: 2025-10-15

This style is clear, simple, and used in international business, aviation, and science. It avoids confusion between day and month order.

Writing Dates in Different Styles

Different contexts call for different date styles.

Context	British English	American English
Formal Writing	15 October 2025	October 15, 2025
Informal Writing	15/10/25	10/15/25
With Day of Week	Monday 15 October 2025	Monday, October 15, 2025
Numeric (business)	2025-10-15	2025-10-15

Always choose one format and use it consistently throughout your document.

Special Cases & Edge Rules

Some situations don’t follow the usual date-writing rules. These special cases help you handle months, years, and abbreviations correctly in any context.

Month and Year Only

If no day is given, exclude commas in both styles:

• September 2025 (not September, 2025)
• 2025 October (rare, but in some contexts)

Many style guides recommend no “of” in this case: December 2011, not December of 2011.

Abbreviating Months & Days

You may shorten months (Jan., Feb., Sept., Oct.) and days (Mon, Tues, Wed) — but avoid abbreviations in formal writing. Always capitalize when they appear.

Non-Breaking Space

In print and web, use a non-breaking space between day and month (e.g. 15 October), so they stay together on one line. This avoids awkward line breaks.

Common Mistakes When Writing Dates

Avoid these common errors:

1. Mixing British and American formats in one text.
2. Forgetting the comma after the day in American dates.
3. Writing months in lowercase letters.
4. Using “of” or “the” in formal writing.
5. Adding unnecessary apostrophes to centuries or decades.
6. Using only numbers without clarifying the format.

Staying consistent keeps your writing clear and professional.

How to Say Dates in English

When speaking dates, English users generally:

• Use ordinal numbers for days (e.g. first, second, twentieth)
• Use cardinal for years (in groups)
• Include “of” or “the” in British variants

Examples (U.S. style):

• Written: October 15, 2025 → Spoken: October fifteenth, twenty twenty-five
• With weekday: Monday, October fifteenth, twenty twenty-five

British style spoken:

• Written: 15 October 2025 → Spoken: the fifteenth of October, twenty twenty-five
• You might also hear: October the fifteenth, twenty twenty-five

Years pronunciation tips:

• 1804 → eighteen oh four
• 1963 → nineteen sixty-three
• 2025 → twenty twenty-five (or two thousand twenty-five — both acceptable)
• 2000–2009 → usually two thousand one, two thousand two
• 2010 onward → twenty ten, twenty eleven, etc. are common.

Examples:

• Written: October 15, 2025
• Spoken: October fifteenth, twenty twenty-five

For British English:

• Written: 15 October 2025
• Spoken: the fifteenth of October, twenty twenty-five

This difference is important when listening or reading aloud.

Tips to Remember

• Use capital letters for months.
• Use commas in American English but not in British English.
• Use words in formal writing and numbers in informal writing.
• Stay consistent throughout your document.
• Always check your audience before choosing a format.
• Say dates naturally: Use ordinals for days and pronounce years in pairs (like “twenty twenty-five”).

Conclusion

You now know how to write dates in English with confidence. Whether you write 15 October 2025 or October 15, 2025, your format depends on your region and audience.

Use words in formal writing, be consistent with your format, and avoid common mistakes. With practice, you’ll write dates clearly, correctly, and professionally every time.

FAQs About Writing Dates in English

Q: What is the correct date format for formal writing?
A: Use full words — “15 October 2025” (British) or “October 15, 2025” (American). Avoid using only numbers.

Q: What is the international standard format?
A: The ISO format, written as YYYY-MM-DD (for example, 2025-10-15).

Q: Should I use commas when writing dates?
A: Yes, in American English — “October 15, 2025.” No commas are used in British English — “15 October 2025.”

Q: Is it okay to abbreviate months?
A: Only in informal writing. In formal writing, always spell out the full month name.