Time Calculator

This time calculator can be used to add, subtract, multiply, and divide time in days, hours, minutes, and seconds. To add or subtract, just provide two times. To multiply or divide, just provide one time and one factor and click the "Calculate" button.

Measurement of time

Time is typically measured using some form of a clock or a calendar; clocks are used for periods less than a day while calendars are used for longer periods. This calculator is mainly concerned with time calculations concerning clocks. Although the number of days can also be calculated, the calendar system is not a focus of this calculator, since the calculator only measures units of time without reference to dates. Use the Date Calculator for calculations concerning dates and to learn more about the Gregorian calendar system.

Using this calculator only requires an understanding of some basic units of time and how to convert between each unit:

1 day = 24 hours = 1,440 minutes = 86,400 seconds

1 hour = 60 minutes = 3,600 seconds

1 minute = 60 seconds

Adding time

There are a few ways to approach adding time without the use of a calculator, all of which involve using the time conversions listed above.

Method 1:

One way to add time is to first add each unit of time involved separately. Then, starting with the smallest unit of time, convert to larger units of time where possible. For example, add 12 hours (h) 45 minutes (m) 67 seconds (s) and 123 h 30 m:

12 h + 123 h = 135 h

45 m + 30 m = 75 m

67 s

67 seconds is equal to 1 minute 7 seconds, so we shift the 1 minute to the next level to get 75 m + 1 m = 76 m. 76 m is equal to 1 hour 16 minutes, so we shift the 1 hour to the next level to get 135 h + 1 h = 136 h leaving us with a solution in terms of hours, minutes, and seconds:

136 h 16 m 7 s

In this case, we can also convert the hours to days (d) if so desired by dividing the number of hours by 24 and keeping the remainder. The remainder is the number of hours. Thus, 136 h = 5 d 16 h, giving us the final solution in days, hours, minutes, and seconds:

5 d 16 h 16 m 7 s

Method 2:

Another way to convert time is to first convert all the times to the smallest unit of time desired, then adding them. Then, divide by the appropriate conversion factor while noting the remainder. The remainder is the smallest unit of time and the dividend is the next largest unit of time. Continue this process of dividing the next largest unit of time with remainder until the time has been converted to the desired units of measurement. Using the same example as above, 12 h 45 m 67 s + 123 h 30 m:

12 h 45 m 67 s =	(12 × 3600 + 45 × 60 + 67)s
=	(43,200 + 2700 + 67)s
=	45,967 s

123 h 30 m =	(123 × 3600 + 30 × 60)s
=	(442,800 + 1,800)s
=	444,600 s

Adding the two together yields:

45,967 + 444,600 = 490,567 s

Now, convert back to next largest unit of time, which is minutes, while keeping the remainder:

490,567 s ÷ 60 = 8,176 m 7 s

Next, convert 8,176 minutes to hours and minutes:

8,176 m ÷ 60 = 136 h 16 m

Then, convert 136 h to days and hours:

136 h ÷ 24 = 5 d 16 h

Adding this all together, the final time is

5 d 16 h 16m 7 s,

which is the same result obtained using Method 1 above.

Subtracting time

Subtracting time can be done in the same manner as adding time. If use the same approach as the method 2 of addition, first, convert all the times to the smallest unit of time involved. After that, subtract the times, then convert back to the desired units of time. For example, subtract 12 hours (h) 45 minutes (m) 67 seconds (s) from 123 h 30 m:

12 h 45 m 67 s =	(12 × 3600 + 45 × 60 + 67)s
=	(43,200 + 2,700 + 67)s
=	45,967 s

123 h 30 m =	(123 × 3600 + 30 × 60)s
=	(442,800 + 1,800)
=	444,600 s

444,600 - 45,967 = 398,633 s

Now, convert to the next largest unit of time, which is minutes, while keeping the remainder:

398,633 s ÷ 60 = 6643 m 53 s

Next, convert 6,643 m to hours and minutes:

6,643 m ÷ 60 = 110 h 43 m

Then, convert 110 h to days and hours:

110 h ÷ 24 = 4 d 14 h

Adding this all together, the final time is:

4 d 14 h 43 m 53 s

Multiplying time

One way to multiply time is to individually multiply each unit of time by the desired factor. Then, starting with the smallest unit of time, convert to the next largest unit of time if necessary. For example, multiply 12 h 45 m 67 s by 3:

12 h × 3 = 36 h

45 m × 3 = 135 m

67 s × 3 = 201 s

Starting with seconds, convert to minutes and seconds:

201 s ÷ 60 = 3 m 21 s

Add the 3 m to 135 m, then convert to hours and minutes:

138 m ÷ 60 = 2 h 18 m

Add the 2 h to 36 h and convert to days and hours:

36 + 2 = 1 d 14 h

Adding this all together, the final time is:

1 d 14 h 18 m 21 s

Dividing time

Same as multiplying time, one way to divide time is to individually divide each unit of time by the desired factor. When dividing time, often the final time will not be solely integers; this will happen if each unit of time is not evenly divisible by the factor. Conventionally, the time will be converted such that the non-integer portion of the time is in smaller units except seconds. This means that any decimals in larger units of time need to be converted to the next smallest unit of time. When converting the time after division, start from the largest unit of time with a decimal portion, then convert the decimal portion of the next smallest unit of time. Add the decimal portion to the next smallest unit of time; if the decimal portion was in hours, convert it to minutes then add it to the minutes portion of the time. Repeat this process until the only unit of time with a decimal is seconds. For example, divide 14 h 47 m 67 s by 3:

14 h ÷ 3 = 4.6667 h

47 m ÷ 3 = 15.6667 m

67 s ÷ 3 = 22.3333 s

Now, take the decimal portion of 4.6667 h and convert it to minutes. There are 60 minutes in an hour, so we multiply the decimal portion by 60 to find the number of minutes it represents:

0.6667 × 60 = 40 m

Next, add the above number of minutes to the minutes portion of the time to get

15.6667 + 40 = 55.6667,

then convert the decimal portion of this to seconds. There are 60 seconds in a minute, so multiply the decimal portion by 60 to find its representation in seconds:

0.6667 × 60 = 40 s

Add this to the seconds portion of the time to get:

22.3333 + 40 = 62.3333 s

Since the seconds now exceed 60, add 1 back to the minutes portion which gives us the final time:

4 h 56 m 2.3333 s

Note that in this example, decimals were rounded to 4 decimal places to make the computations simpler.