en.wikipedia.org/wiki/Day

A **day** is a unit of time. In common usage, it is either an interval equal to 24 hours
or daytime, ... The unit of measurement "**day**", redefined in 1960 as 86 400 SI
**seconds** and symbolized d, ... The life patterns of humans and **many** other
species are related to Earth's solar **day** and the **day**-night cycle (see circadian
rhythms).

www.rapidtables.com/calc/time/seconds-in-day.htm

**Seconds** in a **day** calculation. One **day** has 24 ... has 60 **seconds**, so: 1 **day** = (24
hours/**day**) × (60 minutes/hour) × (60 **seconds**/minute) = 86400 **seconds**/**day** ...

www.quora.com/How-many-seconds-are-there-in-a-day

A **day** typically consists of 23 hours 56 minutes and 4.1 **seconds** to be exact. So if
we are exact then a **day** would consist of 23x60x60 + 56x60 + 4.1 **seconds** ...

socratic.org/questions/how-many-seconds-are-in-a-24-hour-day

May 28, 2017 **...** Well there are 60 **seconds** in a minute and 60 minutes in an hour and 24 hours in
a **day**. Thus: 60⋅60⋅24=86,400 **seconds** in a **day**.

www.unitjuggler.com/convert-time-from-day-to-s.html

Convert time units. Easily convert **days** to **seconds**, convert **day** to **sec**. . **Many**
other converters available for free.

www.unitarium.com/time

Convert time between various time units. For example: See **how many seconds**
are in a hour, **day**, week, year.

www.reference.com/science/many-seconds-day-3f8895e99a57abc9

There are 86400 **seconds** in a **day**. This calculation is based on the conventional
definition of the length of a **day**; for convenience, a **day** is defined as 24 hours.