Time Calculator
Add or subtract hours, minutes and seconds, and see the total in several formats, or the clock time after adding it.
Results
| Item | Value |
|---|
Quick Answer
To add times, add the seconds, minutes and hours separately, then carry every 60 seconds into a minute and every 60 minutes into an hour. 2:45:30 + 1:30:45 − 0:20:00 = 3:56:15. Starting at 9:00 AM, that takes you to 12:56:15 PM.
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Table of Contents
- Time Calculator
- Quick Answer
- Related Calculators
- How This Time Calculator Works
- How to Use the Time Calculator
- Core Formulas
- Key Terms
- Worked Example
- Real-Life Examples
- Time Calculator vs Time Duration Calculator
- Minutes to Decimal Hours
- Tips for Working with Time
- Common Mistakes to Avoid
- Frequently Asked Questions
- References & Sources
How This Time Calculator Works
Enter up to three times in hours, minutes and seconds, and choose whether to add or subtract each one. The calculator turns everything into seconds, adds it up, and shows the total in several formats. Add a start clock time to see what time it will be.
Quick explanation: total seconds = hours × 3,600 + minutes × 60 + seconds.
- Add or subtract: choose for Time 2 and Time 3.
- Formats: h:mm:ss, decimal hours, minutes, seconds, and days.
- Clock time: optional, to find an end time.
How to Use the Time Calculator
- Enter the first time in hours, minutes and seconds.
- Enter a second time and choose whether to add or subtract it.
- Add a third time if you need one, or leave it at zero.
- Optionally, enter a start clock time to see the end time.
- Press Calculate to see the total in h:mm:ss, decimal hours, minutes and seconds.
Core Formulas
- To seconds: h × 3,600 + m × 60 + s
- Hours: total seconds ÷ 3,600, rounded down
- Minutes: remaining seconds ÷ 60, rounded down
- Decimal hours: total seconds ÷ 3,600
Time uses base 60, so 60 seconds make a minute and 60 minutes make an hour. That is why 0:45 + 0:30 is 1:15, not 0:75.
Key Terms
- Base 60: a counting system where 60 of one unit make the next, as with seconds and minutes.
- Decimal hours: time written as a decimal number of hours, such as 1.5 for 1 h 30 min.
- h:mm:ss: hours, minutes and seconds separated by colons, such as 3:56:15.
- Duration: a length of time, as opposed to a time of day.
Worked Example
You drive 7 h 50 min on day one, 8 h 25 min on day two and 6 h 40 min on day three.
- Minutes: 50 + 25 + 40 = 115 min = 1 h 55 min
- Hours: 7 + 8 + 6 + 1 = 22 h
- Total = 22:55:00, or 22.9167 decimal hours
Real-Life Examples
- Video editing: clips of 3:25, 4:50 and 2:15 (minutes:seconds) add up to 0:10:30.
- Cooking: a roast needs 2 h 15 min plus 20 min resting. Starting at 4:30 PM, it is ready at 7:05 PM.
- Race splits: a 1:52:40 half marathon minus a 55:10 first half means the second half took 0:57:30.
- Payroll: 37 h 45 min is 37.75 decimal hours, the format many pay systems need.
Time Calculator vs Time Duration Calculator
- Time Calculator: adds or subtracts lengths of time, such as 2 h 30 min + 45 min.
- Time Duration Calculator: finds the time between two clock times or dates, such as 9:15 AM to 5:40 PM.
- Time Card Calculator: totals a week of work shifts with breaks and overtime.
Minutes to Decimal Hours
| Minutes | Decimal hours |
|---|---|
| 5 | 0.0833 |
| 6 | 0.1 |
| 10 | 0.1667 |
| 12 | 0.2 |
| 15 | 0.25 |
| 20 | 0.3333 |
| 30 | 0.5 |
| 40 | 0.6667 |
| 45 | 0.75 |
| 50 | 0.8333 |
Tips for Working with Time
- Carry at 60: do not treat minutes like decimals.
- Decimal hours: 1.5 hours is 1 hour 30 minutes, not 1 hour 50 minutes.
- Crossing midnight: the clock result shows +1 day when you pass midnight.
- Time zones: use our Time Zone Calculator when places are in different zones.
Common Mistakes to Avoid
- Adding minutes like decimals. 1:45 + 0:30 is 2:15, not 1:75 or 2:75.
- Reading decimal hours as minutes. 2.25 hours is 2 h 15 min.
- Forgetting midnight. 11 PM plus 3 hours is 2 AM the next day.
- Mixing time zones. Convert to one zone before adding.
- Rounding too early. Keep seconds until the end for accurate totals.
Frequently Asked Questions
Add the minutes, then the hours. If the minutes reach 60 or more, subtract 60 and add 1 to the hours.
Subtract seconds, then minutes, then hours. If a column is too small, borrow 60 from the next column up.
Divide the minutes by 60. For example, 45 minutes is 0.75 hours.
2 hours and 30 minutes.
Enter 8 in the first hours box and your current time as the start clock time.
Yes. If you subtract more than you add, the total shows with a minus sign.
There are 86,400 seconds in a day: 24 × 60 × 60.
Enter each day as a time and keep the sign on Add. For a full week of shifts with breaks and overtime, our Time Card Calculator does more.
Enter the seconds in the seconds box and leave the rest at zero. The total shows in h:mm:ss form, for example 5,000 seconds is 1:23:20.
Enter your current time as the start clock time. Leave Time 1 at zero, enter 90 minutes as Time 2, and choose Subtract. The clock time result shows the earlier time.
References & Sources
| Source | Used For | Link |
|---|---|---|
| NIST, Time and frequency | Standard units of time. | https://www.nist.gov/time-distribution |
| Wikipedia, Sexagesimal | Base-60 counting used for time. | https://en.wikipedia.org/wiki/Sexagesimal |