You use time every day. Time helps you plan. You set your alarm. You know when to go to a friend’s house. You check the time for your favorite show. Most of the world uses a simple clock system. This system is the 12 hour clock. It needs two small letter sets to work right. These letters are PM and AM.
These letters tell you if the time is before noon or after noon. You see them often. A store opens at 9 AM. A sports game starts at 8 PM. If you mix up AM and PM, you go to a meeting twelve hours too early. Or you miss your bus by twelve hours. Learning AM and PM is very simple.
What Do AM and PM Mean?
The letters AM and PM come from an old language called Latin. Knowing what they mean makes them easy to remember.
AM stands for Ante Meridiem.
Ante means before. Meridiem means noon or midday.
So, AM means before noon.
PM stands for Post Meridiem.
Post means after. Meridiem means noon or midday.
So, PM means after noon.
This is the main rule. AM is the first part of the day. PM is the second part of the day.
AM is the Morning Time
AM is the time that happens before noon. Think about when you sleep and when you wake up.
The AM time starts at 12:00 AM. This is midnight. Midnight is the very start of a new day.
Time goes up from midnight.
- 1:00 AM is one hour past midnight. You are sleeping.
- 3:00 AM is deep in the night.
- 6:00 AM is when your alarm might ring. You start your day.
- 10:00 AM is when you work or go to school.
The AM time cycle ends at 11:59 AM. One minute after 11:59 AM, the time changes. It becomes PM.
Use AM for any time from 12:00 midnight up to 11:59 AM. If you meet for breakfast, you pick 7:00 AM. If you drive home very late, you do it at 2:00 AM.
PM is the Afternoon and Night Time
PM is the time that happens after noon. Think about when you eat lunch and when you rest in the evening.
The PM time starts at 12:00 PM. This is noon. Noon is the middle of the day. The sun is often highest then.
Time keeps counting from noon.
- 1:00 PM is one hour after lunch. You might be back at work.
- 4:00 PM is late afternoon. The school day ends.
- 7:00 PM is a common time for dinner.
- 11:00 PM is close to bedtime.
The PM time cycle ends at 11:59 PM. When the clock ticks to the next minute, it becomes 12:00 AM. The day is over.
Use PM for any time from 12:00 noon up to 11:59 PM. If you watch a movie at night, it starts at 9:00 PM. If you plan a late lunch, you set it for 1:30 PM.
The Hard Part 12 AM and 12 PM
The times that confuse people most are 12:00 AM and 12:00 PM. Remember this simple trick.
12:00 PM is Noon. This is the time you eat lunch. PM is when People are active. PM is in the daylight.
12:00 AM is Midnight. This is the time you are sleeping. AM starts when you are Asleep. AM is in the dark night.
When you make a plan for noon or midnight, it is best to write the word out.
- Instead of 12:00 PM, write 12:00 noon.
- Instead of 12:00 AM, write 12:00 midnight.
This simple change keeps your plans perfectly clear.
Read: PM en AM: Your Ultimate Guide to Never Confuse Time Again
Why Use the 24 Hour Clock?
The 12 hour clock is old. It has been used for thousands of years. But it has the small risk of mixing up AM and PM.
The 24 hour clock solves this problem. This clock uses numbers from 0000 to 2359. It never uses AM or PM. It is a single, clear loop.
- 1:00 AM is 0100 hours.
- 12:00 PM (noon) is 1200 hours.
- 1:00 PM is 1300 hours.
- 11:00 PM is 2300 hours.
You use the 24 hour clock for jobs where time must be exact. Pilots, doctors, and train workers use it. This way, no one can think a flight is at 3:00 in the morning instead of 3:00 in the afternoon. It stops all mistakes.
How to Get the Time Right Every Time
You know the meaning of AM and PM. Use these simple steps to make sure your time is correct.
1. Write the Letters
When you set a time, do not skip AM or PM. If you write “Meet me at 6,” your friend does not know if you mean 6:00 in the morning or 6:00 in the evening. Always write 6:00 AM or 6:00 PM.
2. Look at the Sky
Use your memory.
- If the sun is low and coming up, it is the early AM.
- If the sun is high, it is near noon or early PM.
- If the sky is dark and the sun is gone, it is the late PM or the deep AM.
3. Change PM to 24 Hour Time
If you are not sure if a PM time is right, quickly change it to 24 hour time. It is a simple math step. For any PM time except 12:00 PM, you add 12.
- 5:00 PM $\to 5 + 12 = 1700$ hours.
- 9:00 PM $\to 9 + 12 = 2100$ hours.
If your new number is 13 or higher, you know it is a time in the PM afternoon or evening.
You now understand the 12 hour clock fully. You can read schedules, set your watch, and plan your day without any fear of mix ups. You are a time master.
Frequently Asked Questions
What does AM mean?
AM means before noon. It is the time from midnight until noon.
What does PM mean?
PM means after noon. It is the time from noon until midnight.
Is 12 oclock at night AM or PM?
12:00 at night is 12:00 AM. This is the start of the new day.
Is 12 oclock in the day AM or PM?
12:00 in the day is 12:00 PM. This is the middle of the day.
What is 3 PM in 24 hour time?
To find 3 PM, you add 12. $3 + 12 = 15$. So 3 PM is 1500 hours.
Why do some places use the 24 hour clock?
They use it for perfect clarity. The 24 hour clock has no AM or PM. It removes any chance of making a time mistake.
Final Thoughts
The 12 hour clock has two parts. AM means “before noon.” PM means “after noon.” AM starts at 12:00 midnight and ends at 11:59 AM. PM starts at 12:00 noon and ends at 11:59 PM. The most important things to remember are that 12:00 AM is midnight and 12:00 PM is noon. If you need to be very clear, use the 24 hour clock or simply write the words “noon” or “midnight.” Use these simple rules and your time telling will be perfect.
