How many seconds are in the day

how many seconds are in the day

The arithmetic is the same if you ask how many seconds is a day, how many seconds is in a day, or how many seconds are in a day. Twenty-four hours, sixty minutes in each hour, sixty seconds in each minute. 24 × 60 = 1,440 minutes. 1,440 × 60 = 86,400 seconds.

That civil day is the one on a wall clock that runs from midnight to the next midnight without a leap second and without a daylight-saving jump. It is the number used in ordinary planning, in school sums, and in most timers.

A seconds day in that sense is just the day measured in seconds instead of hours. You are not looking at a different kind of day. You are looking at the same 24 hours, written as 86,400 ticks of a second hand.

Write the three factors if you need to show the work: hours in the day, minutes in an hour, seconds in a minute. The product is the answer. There is no leftover remainder in that product. 24, 60, and 60 are whole numbers, and so is 86,400.

From hours down to seconds

One hour is 3,600 seconds, because 60 × 60 = 3,600. Six hours are 21,600 seconds. Twelve hours are 43,200 seconds. Eighteen hours are 64,800 seconds. The full 24 hours return 86,400. One minute is 60 seconds, so a count of minutes converts by multiplying by 60. Half a day, as 12 hours, is half of 86,400, which is 43,200. A quarter of a day, as 6 hours, is 21,600. These are the same ratios you already know in hours, only scaled.

Count the hours you mean. A full civil day is 24. Multiply hours by 60 to get minutes. Multiply minutes by 60 to get seconds. For a full day the last product is 86,400. If someone asks for seconds and you only have hours, do not add 60 and 60. Multiply. Adding would describe a duration of two minutes, not a conversion. The conversion is a product at each step down the chain.

You can count the seconds in a day. You cannot make the day wait while you finish counting.

When the figure is not 86,400

UTC can insert a leap second, so a rare UTC day has 86,401 seconds, or, if a second were to be skipped, 86,399. Civil timekeeping in ordinary life still treats the day as 86,400 seconds. Leap seconds are a UTC adjustment, not a change to how many minutes a school clock shows in an hour.

A daylight-saving change also disturbs a local civil day. When clocks spring forward by one hour, that local date can contain 23 hours, which is 82,800 seconds of clock time. When clocks fall back by one hour, that local date can contain 25 hours, which is 90,000 seconds of clock time. Those figures follow from 23 × 3,600 and 25 × 3,600. They apply only on the change dates, and only where the clocks actually jump.

If you are writing software that must match a time standard, say which standard. If you are answering a homework question about a day, 86,400 is the expected number. Do not mix leap seconds into a worksheet that never mentioned UTC.

Sunrise-to-sunrise is another length again: it is not defined as 24 hours of 60 minutes. This page counts clock seconds, not the apparent motion of the Sun.