Time and Date Calculations
Time calculations can mean different things depending on what you are trying to measure. You may need to add or subtract lengths of time, determine how much time passed between two clock readings, or find the number of years, months, and days between two calendar dates.
This calculator provides separate tools for each of those situations so that clock time, durations, and calendar dates are handled appropriately.
Duration Math
A duration represents an amount of time rather than a particular time of day. Durations can be added or subtracted, or multiplied and divided when you need to scale an amount of time.
For example, duration math can be useful for adding several work periods, subtracting break time, calculating total project time, or multiplying the length of one task by the number of times it must be performed.
Elapsed Clock Time
Elapsed time measures how much time passes between a starting time and an ending time. This can be useful for work shifts, travel times, events, equipment run times, parking, or other activities with a known start and finish.
When an activity continues past midnight, the ending clock time may appear earlier than the starting time even though it actually occurred on the following day. The Crosses Midnight option accounts for this situation.
Calendar Date Differences
Calendar calculations are different from simply dividing a number of days by 30 or 365. Months have different lengths, and leap years occasionally add an extra day to February.
An exact calendar difference therefore describes the span in years, remaining months, and remaining days. The total number of days can also be useful when you need a single value for the entire period.
Common Uses
A time and date difference calculator can be useful for finding the length of a work shift, calculating time spent on a project, determining the number of days between appointments or events, comparing two dates, or working with durations expressed in days, hours, minutes, and seconds.