24 Hour Clock

How to read a 24 hour clock face

A normal clock makes you guess: is the hand on 7 morning or evening? A 24 hour dial has no second lap, so the hand can only mean one time. Each hour takes 15 degrees of the circle, and each small tick is 15 minutes. These four points are enough to read it at a glance:

• Top: 24 (or 00)

  Midnight. The day starts and ends here.

• Right: 6

  06:00, early morning. A quarter of the day is gone.

• Bottom: 12

  Noon. Half the day is behind you.

• Left: 18

  18:00, 6 PM. Three quarters gone, evening starts.

Why see the whole day on one circle

I built this clock for myself. A 12 hour clock shows you what time it is. This one shows you how much of the day is left, which is the question I am really asking when I look up from work. When the shaded slice passes the bottom, half the day is gone. You feel that in a way "14:10" never makes you feel.

Put it full screen on a second monitor or an old tablet and it becomes a quiet wall clock that keeps the screen awake. It is also an easy way to teach kids the 24 hour clock: the hand walks once around while they are awake and asleep.

12 hour to 24 hour time conversion chart

The rule: for PM hours add 12, and 12 AM becomes 00. Minutes stay the same, so 4:35 PM is 16:35. Military time drops the colon and is read in hundreds.

Ideas for highlighting your day

A period is any stretch of the day you want to see coming. Give it a name, a color and its hours, and it appears on the dial as a band. Some that work well:

• Eating window12:00 to 20:00

  Intermittent fasting, 16:8: eat between 12:00 and 20:00 and fast for the other 16 hours. The band shows at a glance whether the kitchen is open.

• Sleep23:00 to 07:00

  Your sleep window across midnight. Seeing it on the dial makes it obvious how much evening is left before you should be in bed.

• Deep work09:00 to 12:00

  Your best focus hours, kept free of meetings. When the hand enters the band, close the chat apps.

• Workout18:00 to 19:00

  A fixed slot for training, so it stays on the day instead of moving to "later".

• Commute08:00 to 09:00

  Travel time you can see coming, for podcasts, calls or nothing at all.

• No screens21:00 to 23:00

  An hour or two before bed without phones or laptops. Overlap it with Sleep and both stay visible.

Periods and settings on this page are gone when you reload or leave it. In the free PerspecTask app they are saved to your account and show on the clock page and the dashboard clock.

Who uses 24 hour time

Anyone who cannot afford to mix up morning and evening. Hospitals log medication at 22:00, not "10". Pilots and air traffic control work in UTC, called Zulu time. Trains, buses and flights print departures on the 24 hour clock almost everywhere, and computers store times that way too: the ISO 8601 standard writes 2:30 PM as 14:30. In most of Europe, Latin America, Africa and Asia it is simply how people write the time.

Frequently asked questions

What is a 24 hour clock?

A 24 hour clock counts the hours of the day from 0 to 23 instead of 1 to 12 twice. 9 in the morning is 09:00 and 9 in the evening is 21:00, so there is no AM or PM to get wrong. Most of the world writes time this way, and so do hospitals, the military, airlines, trains and computers.

How do you read an analog 24 hour clock?

The hand goes around once per day instead of twice. 24 (midnight) is at the top, 6 in the morning is on the right, 12 noon is at the bottom and 18:00 (6 PM) is on the left. Each hour is 15 degrees of the circle, and each small tick on this clock is 15 minutes. Wherever the hand points is the hour of the day.

Does this 24 hour clock have a minute hand and a second hand?

Yes, both are optional. Turn on Minute hand and Second hand under the clock. The green hand is the hour hand: it reaches the outer ring of hours and turns once a day. The dark minute hand is shorter, turns once an hour and points at the inner minute ring; the thin red second hand turns once a minute. Turn on Minute marks to get that inner ring, labelled 00, 15, 30 and 45.

Can I turn off the shaded part of the day?

Yes. Switch off Highlight time passed under the clock and the dial shows only the hands. Switch it back on to see the slice of the day that is already behind you.

Can I show my fasting or eating window on the clock?

Yes. Under the clock, add a period called Eating window from 12:00 to 20:00 (the common 16:8 schedule), or tap the Eating window example. It shows as a colored band on the dial, and its name and hours are listed under the clock, so you can see how long the window stays open.

Can highlighted periods overlap or run past midnight?

Yes, both. Each period is see-through, so where two overlap you see both colors. A period that ends before it starts, like Sleep from 23:00 to 07:00, wraps past midnight at the top of the dial.

Can I see the tasks I finished today on the clock?

Yes. Check off a task in the list under the clock and a check mark appears on the dial at the time you did it; hover it to see which task it was. You can change the time to add something you did earlier. With a free PerspecTask account this happens by itself: every task you check off in PerspecTask shows up on its 24h clock.

Are my periods saved?

Not on this page: your periods, checked-off tasks and clock settings are gone when you reload or leave it. Create a free PerspecTask account and the 24h clock in the app saves your periods and settings to your account, and shows the tasks you complete there, on every device, on the clock page and on the dashboard clock.

Why is 24 at the top and not 12?

Because the top of the dial is where a turn starts and ends, and a day starts and ends at midnight. Putting midnight at the top means noon falls at the bottom, morning on the right and evening on the left, so the position of the hand matches how far into the day you are.

How do I convert 12 hour time to 24 hour time?

For AM times, keep the hour, except 12 AM, which becomes 00. For PM times, add 12 to the hour, except 12 PM, which stays 12. So 7:30 AM is 07:30, 12:15 AM is 00:15, 3:45 PM is 15:45 and 12:40 PM is 12:40. The minutes never change.

How do I convert 24 hour time to 12 hour time?

If the hour is 13 or more, subtract 12 and add PM: 17:20 is 5:20 PM. If it is 12, add PM: 12:05 is 12:05 PM. If it is 00, write 12 and add AM: 00:30 is 12:30 AM. Any other hour stays the same with AM: 08:10 is 8:10 AM.

What is military time, and how do you say it?

Military time is the 24 hour clock written with four digits and no colon, like 0600 or 1945. It is read in hundreds: 0600 is "zero six hundred hours", 1300 is "thirteen hundred hours", and 1945 is "nineteen forty-five hours". The US military adds a time zone letter, so UTC is Zulu time, written 1300Z.

What time is 1500, 1700 or 2000 in military time?

1500 is 3 PM, 1700 is 5 PM and 2000 is 8 PM. For any military time after 1200, subtract 1200 to get the PM hour: 2130 minus 1200 is 930, so 2130 is 9:30 PM. The full table of hours is on this page.

Is midnight 00:00 or 24:00?

Both are correct and they mean the same moment. 00:00 is the start of a day and 24:00 is the end of the previous one, so "open until 24:00 on Friday" means until the moment Saturday begins. Digital clocks show 00:00. This dial labels the top 24 because it marks where a full day finishes.

How much of the day is left right now?

The clock above answers it live. The shaded slice is the part of the day that has passed, and the line under the time gives the exact share, such as "62% of the day gone", plus the hours and minutes left until midnight in the time zone you picked.

Can I make the clock full screen?

Yes. Press the full screen button at the top right corner of the clock, and press it again or hit Esc to leave. While it is full screen the clock asks your browser to keep the screen awake, so you can leave it on a spare monitor, a tablet or a TV as a wall clock. On iPhone, where web pages cannot use real full screen, it fills the browser window instead.

Can I see the 24 hour time in another time zone?

Yes. Pick a city from the time zone menu under the clock, or UTC for Zulu time. The dial, the digital time and the time left in the day all switch to that zone, including its daylight saving time.

Which countries use the 24 hour clock?

Most of Europe, Latin America, Africa and Asia write times on the 24 hour clock, on train timetables, TV listings and official documents. The 12 hour clock with AM and PM is the everyday format mainly in the United States, Canada, the UK, Australia, India and the Philippines, though many of them still use 24 hour time for transport, medicine and the military.

Is this 24 hour clock free?

Yes. It is free, needs no account, and runs in your browser from your device clock.