Time Calculator

Enter the time values & days into the given calculator to figure out the sum or difference.

(Note: Blank inputs are considered "0")

Start Time


End Time:

Rating & Review


add or subtract time from a date

The calculator will help you schedule your plans by adding or subtracting the custom time inputs from a start time & date.

(Note: Blank inputs are considered "0")

Start Time

AM PM

Start Time

AM PM



End Time

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Time to Decimal

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Time and a Half Calculator

Table of Content

In straightforward terms, this time calculator lets you effectively manage clock time for different events using dynamic customization features that include:

  • Add or subtract two clock times
  • Add and subtract time concerning a starting date and time

To start, follow the guide mentioned as under:

  • Enter the values given in start time & end time fields
  • Select if you want to Add or Subtract times
  • Click Calculate
  • The time calculator will give you accurate calculations for the clock times according to the arithmetic operation you selected

How To Add or Subtract Time?

The best and most straightforward way to calculate times is by time calculator. But if your goal comes up with manual calculations, then the following examples will certainly help you.

Time Addition:

It is preferred to add time by converting all the units in terms of seconds. It will make the calculations quite simple.

Add The Following Times:

4:15:10 & 3:29:03

Step # 01

1 Hour = 60 * 60 sec = 3600 sec

1 Minute = 60 sec

Step # 03

Convert second time in seconds:

3:29:03

= (3*60*60 sec)+(29*60 sec)+(03 sec)

= (10800 sec)+(1740 sec)(03 sec)

= 12543 sec

Step # 05

Calculate Days

1 day = 24 hours

1 day = 24×60×60 sec

1 day = 86400 sec

As we are having a total of 20,653, so we have:

Days = 20,653/86400

Days = 0

Step # 02

Convert first time in seconds:

4:15:10

= (4*60*60 sec)+(15*60 sec)+(10 sec)

= 7200sec+900sec+10sec

= 8110 sec

Step # 04

Add Seconds

= (8110 + 12543) sec

= 20,653 sec

Step # 06

Calculate Hours

Hours = 20,653/3600

Hours = 5.736

Step # 07

Calculate Minutes

Minutes = 20,653/60

Minutes = 344.2

Time Subtraction:

To subtract time, you will again have to follow the same way i.e. keeping the units in sec

Remember that:

  • To subtract times, the first time must be greater than the second time

Subtract The Following Times:

6:40:17 & 1:03:21

Step # 01

Again we have:

1 Minute = 60 sec

1 Hour = 60 * 60 sec = 3600 sec

Step # 03

Convert second time in seconds:

1:03:21

= (1*60*60 sec)+(03*60 sec)+(21 sec)

=(3600 sec)+(180 sec)(21 sec)

= 3801 sec

Step # 05

Calculate Days

1 day = 24 hours

1 day = 24×60×60 sec

1 day = 86400 sec

As we have a total of 20,216, so we have:

Days = 20,216/86400

Days = 0

Step # 02

Convert first time in seconds:

6:40:17

=(6*60*60 sec)+(40*60 sec)+(17 sec)

= 21,600 sec + 2400 sec + 17 sec

= 24,017 sec

Step # 04

Subtract Seconds

= (24,017 - 3801) sec

= 20,216 sec

Step # 06

Calculate Hours

Hours = 20,216/3600

Hours = 5.615

Step # 07

Calculate Minutes

Minutes = 20,216/60

Minutes = 336.0

Time Units:

Unit Definition
millennium 1,000 years
century 100 years
decade 10 years
year(average) 365.242 days or 12 months
common year 365 days or 12 months
leap year 366 days or 12 months
quarter 3 months
month 28-31 days Jan., Mar., May, Jul., Aug. Oct., Dec.—31 days Apr., Jun., Sep., Nov.—30 days. Feb.—28 days for a common year and 29 days for a leap year
week 7 days
day 24 hours or 1,440 minutes or 86,400 sec
hour 60 minutes or 3,600 sec
minute 60 sec
second base unit
millisecond 10-3 second
microsecond 10-6 second
nanosecond 10-9 second
picosecond 10-12 second