AM and PM in English: Usage, 24-Hour Clock, and Exams

AM and PM are common time expressions in English used in the 12-hour clock system. This guide explains their meaning, origin, and differences, shows how to write and pronounce them correctly, compares them with the 24-hour format, and provides IELTS/TOEFL examples plus exercises with answers.

I. What Do AM and PM Mean in English?

In English, AM and PM are abbreviations used to divide the 24 hours of the day into two 12-hour periods on the 12-hour clock system. These labels help distinguish between morning and afternoon/evening times.

AM = Ante Meridiem - The abbreviation AM comes from Latin: ante meridiem, which means “before midday”. It refers to the 12-hour period between midnight (12:00 AM) and noon (11:59 AM).

Examples:

• 6:00 AM = six o’clock in the morning
• 11:30 AM = late morning, before noon

PM = Post Meridiem - PM comes from post meridiem, meaning “after midday”. It covers the time between 12:00 noon and 11:59 at night.

Examples:

• 2:00 PM = two o’clock in the afternoon
• 9:00 PM = evening or nighttime

The 12-hour clock resets halfway through the day:

• From 12:00 AM (midnight) to 11:59 AM → morning hours (AM)
• From 12:00 PM (noon) to 11:59 PM → afternoon to night (PM)

This contrasts with the 24-hour clock, which runs from 00:00 to 23:59. Understanding how AM and PM function is especially important when reading timetables, making appointments, or taking standardized tests.

1. Difference Between AM and PM

Although AM and PM both describe time in the 12-hour clock system, they represent two completely different halves of the day. 

AM vs PM by Hour

• AM (Ante Meridiem):  Covers the time from 12:00 midnight (00:00) to 11:59 in the morning. This period includes early morning activities like waking up, going to school, or commuting to work.
  Example:
  • 6:00 AM = early morning
  • 11:45 AM = late morning, just before noon
• PM (Post Meridiem): Refers to the time from 12:00 noon to 11:59 at night. This includes afternoon, evening, and late-night hours.
  Example:
  • 3:00 PM = mid-afternoon
  • 9:30 PM = night time

This clear division helps distinguish between similar numbers (for example, 7:00 AM and 7:00 PM mean very different times of day).

Is 12 AM Midnight or Noon?

This is one of the most commonly misunderstood points in English timekeeping.

• 12:00 AM = midnight (the start of a new day)
• 12:00 PM = noon (midday)

To avoid confusion:

• Use “12 midnight” instead of “12 AM”
• Use “12 noon” instead of “12 PM”. This is especially helpful in formal writing or when scheduling events across time zones.

2. How to Write and Say AM and PM Correctly

Using AM and PM properly in both written and spoken English is important for clarity, especially in exams, schedules, emails, and spoken communication. Let's look at three key aspects: writing conventions, pronunciation, and style differences between English varieties.

Writing Conventions

• Capitalization: Both “AM” and “PM” are usually written in uppercase letters, especially in formal or printed text (e.g., 10:00 AM). However, lowercase forms such as a.m. or p.m. (with periods) are also acceptable, particularly in publications or older styles.
• Spacing & Formatting: These are all commonly accepted formats:
  • 8:00 AM
  • 8:00 a.m.
  • 8 AM (no colon for simplicity, often used in digital clocks)
• In formal writing or invitations, it's better to clarify:
  • Use 12 noon instead of 12:00 PM
  • Use 12 midnight instead of 12:00 AM

Pronunciation in English

When speaking, native speakers often say:

• "AM" as “ay-em”
  (e.g., “I wake up at six ay-em.”)
• "PM" as “pee-em”
  (e.g., “The meeting is at four pee-em.”)

Style Differences (UK vs US)

In American English:

• Use AM/PM in everyday contexts and digital devices.
• It's more common than the 24-hour clock.

In British English:

• The 24-hour clock is widely used for timetables, official schedules, and transportation.
• However, AM/PM still appears in casual writing and speech about daily routines.

Understanding subtle grammar choices, such as when to use if and whether, also improves academic accuracy.

3. AM and PM vs the 24-Hour Clock

English speakers use two main systems to tell time: the 12-hour clock (with AM and PM) and the 24-hour clock. While both systems are correct, knowing how to interpret and convert between them is essential—especially in tests, travel, and professional environments.

Converting 24-Hour Time to AM/PM

To convert from a 24-hour format to 12-hour time:

• For hours between 00:00 and 11:59, keep the hour and add AM
  Example: 07:30 → 7:30 AM
• For hours between 12:00 and 23:59, subtract 12 and add PM
  Example: 18:45 → 6:45 PM

Special cases:

• 00:00 = 12:00 AM (Midnight)
• 12:00 = 12:00 PM (Noon)

Avoiding Confusion in Schedules

When writing or reading schedules, it's important to choose the format that best fits the audience or context:

• Use AM/PM for:
  • Casual conversation
  • Daily routines
  • Medical or office appointments
• Use 24-hour format for:
  • Flight, train, and bus schedules
  • Military and emergency services
  • International communication

In some cases—especially in academic exams or formal writing—it’s a good idea to write times clearly and consistently, and avoid switching formats in the same text. To express duration more accurately, don’t forget to review for and since.

II. AM and PM in English Exams and Learning

Understanding how to use AM and PM correctly is not only essential in daily communication but also highly relevant in standardized English exams such as IELTS, TOEIC, and TOEFL. Test-takers are often required to understand or provide time-related information in both spoken and written formats, particularly in Listening and Speaking tasks.

AM and PM in Listening Sections

• In IELTS Listening and TOEIC Listening Parts, learners frequently hear appointment times, train or flight schedules, meetings, and class timetables that include “AM” or “PM.” Misunderstanding time references can lead to selecting the wrong answers in multiple-choice or form-completion questions.
• Example – IELTS Form Completion: "The interview will begin at 9:15 AM, and candidates should arrive 15 minutes early."

AM and PM in IELTS/TOEFL Speaking

• Time expressions are useful when discussing your daily routine, work schedule, or study plans—topics that often appear in Part 1 and Part 2 of IELTS Speaking.
  • Sample question: “What time do you usually wake up?”
  • Sample answer: "I usually wake up at 6:30 AM because I like to exercise before I go to work."
• Using “AM” and “PM” naturally and confidently demonstrates fluency and accuracy in time description.

III. Exercises on AM and PM with Answers

Below are interactive exercises designed to help learners recognize, apply, and convert time between formats accurately. These exercises reflect situations commonly found in exams and real-life communication.

Exercise 1: Fill in the Blanks

Complete the sentences with a logical time using AM or PM.

1. I usually have breakfast at __________.
2. The movie starts at __________ tonight.
3. She has a dentist appointment at __________ tomorrow morning.
4. The train leaves at __________ in the evening.
5. We arrived at school at __________.

Change the following 24-hour times into 12-hour format with AM or PM.

Exercise 3: Correct the Mistakes

Each sentence below has an error in how the time is expressed. Rewrite the sentence correctly.

1. We will meet at 12:00 AM for lunch.
2. My class finishes at 3:30 PM in the afternoon.
3. Let’s wake up at 07:00 PM to catch the sunrise.
4. The bus leaves at 14:00 AM.
5. I eat dinner at 8 PM in the morning.

Answers

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Overall, PREP hopes this has provided you with a comprehensive understanding of the concept and usage of AM and PM in English. If you want to build a strong foundation, don’t forget to review the basics of learn English grammar.