Time Duration Calculator: Calculate Time Between Two Times
Calculating the duration between two times is essential for payroll, project tracking, travel planning, and daily scheduling. Our Time Duration Calculator computes the exact hours, minutes, and seconds between two times, handles AM/PM and 24-hour formats, and accounts for overnight durations that cross midnight. Calculate work hours, travel time, or any time interval with precision. Use our Time Duration Calculator to estimate your costs.
How Time Duration Works
Time duration is calculated by subtracting the start time from the end time. Simple for times within the same day: 9:00 AM to 5:00 PM = 8 hours. More complex when crossing midnight: 10:00 PM to 6:00 AM = 8 hours. The calculator handles this by adding 24 hours when the end time is earlier than the start time (indicating an overnight period).
The calculator supports both 12-hour (AM/PM) and 24-hour (military) time formats. It also calculates durations that span multiple days by including the date with the time entry.
Using the Time Duration Calculator
Enter the start time and end time. Select AM or PM for each (or use 24-hour format). For durations spanning multiple days, enter the start and end dates as well. The calculator shows the total duration in hours, minutes, and seconds, as well as the duration in decimal hours for payroll calculations.
The calculator includes time addition and subtraction: add or subtract hours and minutes from a specific time to calculate a future or past time. Useful for determining when a task will be completed given its duration.
Common Use Cases
Work Hours and Payroll
Calculate hours worked between clock-in and clock-out times. Subtract unpaid lunch breaks. The calculator shows total hours in both HH:MM format and decimal hours (8.5 hours instead of 8:30) for direct use in payroll systems.
Travel Time
Calculate the duration of flights, road trips, or train journeys. Enter departure and arrival times, accounting for time zone changes if applicable. The calculator can subtract layover or stop times.
Project and Task Timing
Track how long specific tasks take. Enter start and end times to calculate duration. Use the time addition feature to estimate completion times for tasks with known durations.
Exercise and Workouts
Track workout duration, rest periods between sets, and total exercise time. The calculator handles multiple intervals and can sum them for total workout time.
Time Format Conversions
- Hours and minutes to decimal: Divide minutes by 60. 8 hours 30 minutes = 8.5 hours. 2 hours 45 minutes = 2.75 hours.
- Decimal to hours and minutes: Multiply decimal portion by 60. 3.75 hours = 3 hours 45 minutes. 1.33 hours = 1 hour 20 minutes.
- 12-hour to 24-hour: 12:00 AM = 00:00. 12:00 PM = 12:00. 1:00 PM = 13:00. 11:00 PM = 23:00.
- Minutes to hours: Divide by 60. 150 minutes = 2.5 hours = 2 hours 30 minutes.
Real-World Example
An employee works the following shift: clock in at 8:45 AM, clock out for lunch at 12:30 PM, clock back in at 1:15 PM, clock out at 5:30 PM:
- Morning shift: 8:45 AM to 12:30 PM = 3 hours 45 minutes
- Lunch break: 12:30 PM to 1:15 PM = 45 minutes (unpaid, subtracted)
- Afternoon shift: 1:15 PM to 5:30 PM = 4 hours 15 minutes
- Total hours worked: 3:45 + 4:15 = 8 hours
- Decimal equivalent: 8.0 hours for payroll
If the employee needs to know what time 3.5 hours after 10:15 AM would be: 10:15 + 3:30 = 1:45 PM.
Start Calculating
Use our Time Duration Calculator below to calculate intervals between times, add or subtract time, and convert between time formats. Also check our Date Difference Calculator for date spans and our Time Zone Converter for converting between time zones.
Common Time Duration Mistakes
The most frequent error is forgetting the overnight checkbox when a shift crosses midnight. Enter 10:00 PM to 6:00 AM without checking it and the calculator alerts you because 6:00 AM falls earlier than 10:00 PM on the same day; tick "Overnight (crosses midnight)" and it correctly reports 8 hours. A second common mistake is mixing 12-hour and 24-hour conventions — entering 15:30 as 3:30 and then misreading the result by 12 hours. A third trap is 12:00 itself: on the 12-hour clock, 12:00 AM is midnight and 12:00 PM is noon, so a shift from 12:00 PM to 2:00 PM is 2 hours, while 12:00 AM to 2:00 AM covers a different stretch of the day. Finally, watch how you convert minutes: 1.5 hours equals 90 minutes (not 1 hour 50 minutes), and 8 hours 30 minutes must be written as 8.5 decimal hours for payroll systems that bill in tenths of an hour.
Related Calculators
Use our Time Duration Calculator Guide together with related tools such as Age Calculator, Anniversary Calculator, Business Days Calculator to plan more accurately. Each calculator runs instantly in your browser with step-by-step guidance.
Written by the CalcMaster Pro Editorial Team — financial, health, and DIY tools reviewed for accuracy. All calculators run on standard, widely accepted formulas. Always confirm final numbers with a qualified professional for decisions that require official figures.