Days Transformed to Seconds

To convert day [d] to second [s], or to go the other way around, please enter the values below. If you need assistance, you can click on the following link: here.

Explanation: A day (symbol: d) is a time unit that is not part of the International System of Units (SI). It is defined based on the SI unit of time, the second, and is equal to 86,400 seconds.

Historical Background: The term "day" comes from the Old English word "dæg." It roughly corresponds to the time it takes for the Earth to complete one full rotation around the sun. In 1960, it was redefined in relation to the second, which itself had been defined in terms of Earth's orbital motion in 1900. In 1967, both the second and the day were redefined again, this time based on atomic electron transition.

Current Usage: The day is a widely used term across various contexts, often referring to a 24-hour time interval. It can also denote daytime, when the sun is above the horizon. Furthermore, it has colloquial applications such as referencing the days of the week or fixed clock periods like 6:00 am to 6:00 pm.

The Second

Explanation: The second is the fundamental unit of time in the International System of Units (SI). It is defined based on the frequency of cesium, known as ΔνC, which is equivalent to 9,192,632,770 hertz (s-1).

Historical Background: Unlike many other units, the second has had only four different definitions throughout history.

In 1832, the second was defined as 1/86400 of a day, using the approximate duration of Earth's rotation cycle.

In the late 1940s, with the introduction of quartz crystal oscillator clocks, the second was defined as a fraction of an extrapolated year. This led to the specific value of "1/31,556,925.9747 of the tropical year for 1900 January 0 at 12 hours ephemeris time," which became part of the SI in 1960.

In 1967, the second was exactly defined as "9,192,631,770 times the period of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom." This definition was updated in late 2018 to provide more precise conditions, while remaining effectively the same. This refinement does not impact everyday usage of the second.

Current Usage: As the SI base unit of time, the second and its multiples are widely utilized. Almost all modern applications measure time in terms of the second and its multiples.

Day [d]Second [s]0.01 d = 864 s0.1 d = 8640 s1 d = 86400 s2 d = 172800 s3 d = 259200 s5 d = 432000 s10 d = 864000 s20 d = 1728000 s50 d = 4320000 s100 d = 8640000 s1000 d = 86400000 s1 d = 86400 s1 s = 1.15741E-5 d

An illustration: transforming 15 days into seconds: 15 days equals 15 multiplied by 86400 seconds, resulting in 1296000 seconds.