Times of day

How a time countdown works

A date count moves once a day, but a clock time count moves every second. Open a page and it works out the next time the clock will read that hour in your zone.

If the time has not come yet today, it counts to later today. If it has gone by, it counts to the same time tomorrow and says so.

The page asks your browser for its time zone, so a visitor in Sydney and one in Denver each see their own wall clock.

12-hour and 24-hour time

The US uses the 12-hour clock with AM and PM in daily speech. Most of the world, and most timetables, use the 24-hour clock instead.

On the 24-hour clock, the hours after noon add twelve. So 5 PM is 17:00, and 11 PM is 23:00.

Military time writes the same thing with no colon. It is said as hundreds, so 1700 is "seventeen hundred hours".

Midnight and noon

Midnight and noon cause the most confusion, because AM and PM do not fit them well. We label them by name, and show 00:00 and 12:00 beside them.

12 AM means the start of the day, and 12 PM means the middle of it. Many people avoid both and write midnight or noon.

A deadline "at midnight" is also unclear. It can mean the start or the end of a date, so check which day is meant.

Across time zones

The same clock time is a different moment in each city. Each page includes a table that shows the local time in cities such as Auckland, Sydney, Perth, Tokyo, Dubai, Nairobi.

Daylight saving time moves clocks forward and back. The US, Europe and Australia change on different dates, so gaps between cities shift for a few weeks a year.

That is why a countdown uses your own zone rather than one fixed zone. It always shows the time left on your wall clock.

Shift work and schedules

Shift workers count down to the end of a shift more than to any date. A page for 5 PM or 6 PM shows the time left to the minute, and it updates as you watch.

Night shifts are harder, because the end falls after midnight. The page picks the next time that matches, so it still gives the right answer at 3 AM.

Teams in different cities can use the world table on each page to agree on a cut-off that is fair to all of them.

Why we only list hours and half hours

The pages cover every hour and half hour, which are the times people search for. A countdown to an odd minute, like 4:47 PM, is better answered by the countdown tool.

The question box accepts a time in many forms. It reads "5pm", "17:00" and "half past five", and sends you to the closest page.

If your time is not on the list, the box opens the tool with it filled in.

Time zones and daylight saving

Your device knows its own time zone, so the page does not ask where you are. It uses that zone to find the next time the clock will show your chosen hour.

On the day clocks change, a day is 23 or 25 hours long. The count handles this by working from the real clock, so the answer stays correct across the change.