Time Calculator
Use this free time calculator to add, subtract, multiply or divide time, find the hours between two clock times, or convert time to decimal hours. Also, results update as you type.
Built and tested by the CalcPro team · Last updated October 27, 2026
First time
Second time
Clock times
If the end time is earlier than the start time, it counts as the next day. Also, use the break box for work hours.
Starting clock time
Amount of time
Time
One time per line
Type each time as h:mm, h:mm:ss or like 2h 15m 30s. Also, start a line with − to subtract it.
Time to decimal hours
Decimal hours to time
Time expression
Use d, h, m and s for days, hours, minutes and seconds. Then put + or − between terms.
Result
How the time calculator works
First, time doesn’t use base-10 like ordinary decimal numbers. Instead, seconds and minutes run in base-60, and hours run in base-24. As a result, adding 45 minutes and 30 minutes doesn’t give “75 minutes”. Rather, it carries over into 1 hour and 15 minutes, just as carrying works in long addition. Therefore, this time calculator handles that conversion for you automatically.
Worked example: start with 2 hours 15 minutes 30 seconds and add 4 hours 50 minutes 15 seconds. First, convert both to seconds: 8,130 and 17,415. Then add them to get 25,545 seconds. Converted back, that is 7 hours 5 minutes 45 seconds.
How to use each time calculator mode
Besides these tabs, the Expression tab is for shorthand fans. For example, 1d 2h 3m 4s + 4h 5s - 2030s gives the whole answer in one line.
How to add hours and minutes with the time calculator
First, open the Add / Subtract tab and enter the first time. Then choose Add and enter the second time. For example, 3 hours 40 minutes plus 2 hours 35 minutes equals 6 hours 15 minutes. Meanwhile, if you have many times to add, use the Add a List tab and type one time per line.
How to convert time to decimal hours
First, payroll and timesheets often need decimal hours, so this conversion matters. To convert, first divide the minutes by 60. Then add the result to the hours. For instance, 7 hours 45 minutes is 7 + 45/60, which equals 7.75 hours. Likewise, 0.25 hours is 15 minutes. Because the Decimal Hours tab works both ways, you can switch easily. If you then need pay, try the overtime pay calculator.
Minutes to Decimal Hours Chart
Many timesheets ask for hours in decimals, so this quick chart saves time. For example, 15 minutes is 0.25 hours, because 15 divided by 60 equals 0.25. Also, you can use the Decimal Hours tab for any other value.
| Minutes | Decimal hours |
|---|---|
| 1 minute | 0.02 hours |
| 5 minutes | 0.08 hours |
| 10 minutes | 0.17 hours |
| 15 minutes | 0.25 hours |
| 20 minutes | 0.33 hours |
| 30 minutes | 0.50 hours |
| 40 minutes | 0.67 hours |
| 45 minutes | 0.75 hours |
| 50 minutes | 0.83 hours |
| 55 minutes | 0.92 hours |
| 60 minutes | 1.00 hour |
How to Calculate Hours Worked Between Two Times
First, open the Time Between tab and enter your start and end times. Then type any unpaid break in minutes. For example, a shift from 9:00 to 17:30 lasts 8 hours 30 minutes. However, after a 30-minute unpaid break, you worked 8 hours, which is 8.00 in decimal hours. In the same way, a 9 to 5 day with no break is 8 hours, and with a 30-minute break it is 7.5 hours.
Units of time used by the time calculator
Time math depends on how each unit converts into the next. Also, the second itself is defined by international standards, which you can read about at NIST Time and Frequency Division.
| Unit | Definition |
|---|---|
| Decade | 10 years |
| Year (average) | 365.242 days, or 12 months |
| Month | 28–31 days, depending on the month |
| Week | 7 days |
| Day | 24 hours, or 1,440 minutes, or 86,400 seconds |
| Hour | 60 minutes, or 3,600 seconds |
| Minute | 60 seconds |
| Second | Base unit of time |
| Millisecond | 0.001 second |
Common uses for a time calculator
- Tracking work hours: find the gap between clock-in and clock-out, then total a week of shifts. Use the pro rata salary calculator for part-time pay.
- Cooking and baking: add prep time and cook time, so you know when a dish will be ready.
- Travel planning: work out an arrival time from a departure time and a trip length. Also, the distance calculator helps with the trip length.
- Study and workouts: total several blocks, for example interval training or study sprints.
- Project scheduling: estimate a finish time, then add buffer by adding an expected duration to a start time.
Tips for accurate time calculator results
- Also, leave unused fields blank. Since blanks count as zero, you don’t need to fill in days or seconds.
- Negative results are valid. However, a minus sign simply shows how far short the first time falls.
- Midnight is handled for you. Therefore, in Time Between mode an earlier end time counts as the next day.
Frequently asked questions
How do I add or subtract time correctly?
First, convert both times to one unit, usually seconds. Then add or subtract the totals and convert back into days, hours, minutes and seconds. Fortunately, this calculator does the conversion automatically.
How do I add multiple times together?
First, open the Add a List tab and type one time per line, such as 1:30 and 2:45. Then, as you type, the total appears instantly.
How do I find the hours between two times?
First, use the Time Between tab and enter a start time and an end time. However, if the end is earlier than the start, the calculator treats it as the next day.
How do I convert minutes to decimal hours?
First, divide the minutes by 60. For example, 30 minutes is 0.5 hours and 45 minutes is 0.75 hours. Alternatively, the Decimal Hours tab does this for you.
How do I multiply time?
First, open the Multiply / Divide tab. Next, enter the time and choose Multiply. Then type the number of repeats, and the calculator shows the answer in days, hours, minutes and seconds.
What happens if the result is negative?
A negative result means the second time is larger than the first. In that case, the calculator shows a minus sign with the size of the difference.
Why doesn’t time math work like normal decimal math?
Because time uses base-60 for seconds and minutes and base-24 for hours, 45 minutes plus 30 minutes carries over to 1 hour 15 minutes. Therefore, ordinary decimal math gives the wrong answer.
How many hours is 9 to 5?
For example, a 9 to 5 workday is 8 hours with no break. However, if you take a 30-minute unpaid break, you work 7.5 hours.
How do I turn 8 hours 30 minutes into decimal hours?
First, divide the 30 minutes by 60 to get 0.5. Then add it to the 8 hours, so the answer is 8.5 decimal hours.
Overall, this calculator is for general time math. However, it does not account for time zone differences or daylight saving changes.