## Conversion formula

The conversion factor from hours to seconds is 3600, which means that 1 hour is equal to 3600 seconds:

1 hr = 3600 s

To convert 21 hours into seconds we have to multiply 21 by the conversion factor in order to get the time amount from hours to seconds. We can also form a simple proportion to calculate the result:

1 hr → 3600 s

21 hr → T(s)

Solve the above proportion to obtain the time T in seconds:

T(s) = 21 hr × 3600 s

T(s) = 75600 s

The final result is:

21 hr → 75600 s

We conclude that 21 hours is equivalent to 75600 seconds:

21 hours = 75600 seconds ## Alternative conversion

We can also convert by utilizing the inverse value of the conversion factor. In this case 1 second is equal to 1.3227513227513E-5 × 21 hours.

Another way is saying that 21 hours is equal to 1 ÷ 1.3227513227513E-5 seconds.

## Approximate result

For practical purposes we can round our final result to an approximate numerical value. We can say that twenty-one hours is approximately seventy-five thousand six hundred seconds:

21 hr ≅ 75600 s

An alternative is also that one second is approximately zero times twenty-one hours.

## Conversion table

### hours to seconds chart

For quick reference purposes, below is the conversion table you can use to convert from hours to seconds

hours (hr) seconds (s)
22 hours 79200 seconds
23 hours 82800 seconds
24 hours 86400 seconds
25 hours 90000 seconds
26 hours 93600 seconds
27 hours 97200 seconds
28 hours 100800 seconds
29 hours 104400 seconds
30 hours 108000 seconds
31 hours 111600 seconds