英文日期与时间写法全攻略

You've written the perfect email, but then you freeze. Is it “June 23” or “23 June”? Do you need a comma after the year? And what about time — is it “2:00 p.m.” or “14:00”?

You're not alone. Dates and times in English trip up even advanced learners. The good news? There are only a handful of patterns to learn. Once you know them, you'll never second‑guess yourself again.

Here’s how to write dates and times the right way.

The Basic Structure of English Dates

English dates follow a simple logic. You start with the day or month, then the month or day, then the year.

Month‑Day‑Year (American Style)

Americans put the month first, followed by the day, then a comma, and finally the year.

• July 4, 1776
• December 25, 2024
• March 15, 2025

Quick tip: Always use a comma after the day when you’re writing a full date. No comma is needed if you’re only writing the month and year (like “March 2025”).

Day‑Month‑Year (British / International Style)

Most of the rest of the English‑speaking world reverses the order. Day comes first, then month, then year. No comma needed.

• 4 July 1776
• 25 December 2024
• 15 March 2025

When in doubt: If you’re writing for an international audience, the day‑month‑year format causes fewer misunderstandings. “4/3” means April 3 in the US but March 4 in the UK — that’s a problem worth avoiding.

Ordinal Numbers: When to Use “th,” “st,” “nd”

This is where many learners overthink it.

In everyday writing (letters, emails, conversations), use ordinal numbers:

• We’re meeting on June 21st.
• Her birthday is March 3rd.
• Our anniversary is October 1st.

In formal documents and official forms, use cardinal numbers:

• The deadline is June 21.
• Payment due by March 3.

Both are correct. Ordinals sound more natural in speech. Cardinals look cleaner on a printed page.

Prepositions: In, On, At

Get these wrong and your dates will sound odd to native speakers. The rule is simple:

Examples in context:

• I’ll see you on Friday.
• The meeting is at 2:30.
• She was born in March.
• The project ends on December 15, 2024, at 5:00 p.m.

Writing Years: The Century Trap

English speakers don’t say years the way you’d expect from reading them.

• 1999 → “nineteen ninety‑nine” (not “one thousand nine hundred ninety‑nine”)
• 2024 → “twenty twenty‑four”
• 1905 → “nineteen oh five”
• 2000 → “two thousand”
• 2005 → “two thousand five” or “twenty oh five”

Important exception: 2010 to 2019 can go either way. “Twenty ten” and “two thousand ten” are both fine. Just pick one and stay consistent.

Time Formats: 12‑Hour vs. 24‑Hour

This one depends entirely on where you are.

A Few Time‑Writing Rules

• Use periods or colons between hours and minutes: 2:30 or 2.30 (both accepted, but colons are more common now)
• Capitalize “a.m.” and “p.m.” — but lowercase is fine too: 3:00 PM or 3:00 p.m.
• No space between the time and a.m./p.m. in American English. British English sometimes adds one: 3:00 p.m. (UK) vs 3:00 p.m. (US)

Combining Dates and Times

Putting it all together requires careful punctuation. Here’s the pattern:

American format: The meeting is on Monday, June 23, 2025, at 2:30 p.m.

British format: The meeting is on Monday, 23 June 2025, at 2.30 p.m.

Notice the commas. They frame the date like parentheses. If you remove “June 23, 2025,” the sentence still works: “The meeting is on Monday at 2:30 p.m.”

The Bottom Line

Writing dates and times in English isn’t about memorizing a hundred rules. You only need three:

1. Pick one format (US or UK) and stick with it
2. Use the right preposition (at, on, in)
3. Keep commas consistent

Everything else is just detail.

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