How to use the time calculator
The calculator has two modes. Pick the one that matches your question.
Add or subtract time
Use this to add up durations, such as video clips, study sessions, run splits or cooking steps.
- Type a time on each row:
2:45,2h 45m,90mor1:02:03for hours, minutes and seconds. - Tap the + button next to a row to switch it to − and subtract it instead.
- Press Enter or Add a row for more times. Each row shows how it was read and the running total so far.
- Read the total in h:mm:ss, in words, and in decimal hours, total minutes and total seconds. Copy result copies the whole sum.
Time from a start time
Use this mode to find the time before or after another time: when a 7½-hour flight lands, when a timer ends, or what time it will be 90 minutes from now.
- Type the start time, for example
9:45 PM,945por21:45, or tap Now for the current time. - Optional: add a start date to get the exact date of the result.
- Choose Add (after) or Subtract (before) and type the duration.
- The end time appears straight away, with +1 day or -1 day when it crosses midnight.
How to add and subtract time
Time is not decimal: there are 60 seconds in a minute and 60 minutes in an hour, so you can't add 2:45 and 3:30 like ordinary numbers. The rule is simple:
- Adding: add each unit separately, then carry. Every 60 seconds becomes 1 minute, and every 60 minutes becomes 1 hour.
- Subtracting: if the top number is too small, borrow 1 from the next unit up and add 60.
Example with carrying: 1:45:50 + 2:30:25
- Seconds: 50 + 25 = 75 seconds = 1 minute 15 seconds. Write 15, carry 1 minute.
- Minutes: 45 + 30 + 1 = 76 minutes = 1 hour 16 minutes. Write 16, carry 1 hour.
- Hours: 1 + 2 + 1 = 4.
- Total: 4:16:15.
Example with borrowing: 5:10 − 2:45. You can't take 45 minutes from 10, so borrow 1 hour: 5:10 becomes 4:70. Then 4:70 − 2:45 = 2:25.
A mixed example: 2 h 45 min + 3 h 30 min − 50 min = 6 h 15 min − 50 min = 5 h 25 min. As decimal hours that's 25 ÷ 60 = 0.4167, so 5.4167 hours. Need a quick lookup instead? The minutes to decimal chart lists every minute from 1 to 59.
Adding time to a clock time
Adding to a clock works the same way, except the clock starts again after 24 hours. Write the start time in 24-hour form, add the duration, and take away 24 hours for each day you pass:
- 7 h 30 min after 9:45 PM: 21:45 + 7:30 = 29:15. Take away 24 hours: 5:15 AM the next day.
- 2 h 20 min before 1:10 AM: 1:10 − 2:20 = −1:10. Add 24 hours: 22:50, so 10:50 PM the previous day.
- 36 hours after Thursday, September 24, 2026 at 9:00 AM is Friday, September 25, 2026 at 9:00 PM.
Worked examples
| Calculation | Result |
|---|---|
| 2 h 45 min + 3 h 30 min − 50 min | 5 h 25 min (5:25:00, 5.4167 h) |
| 1:45:50 + 2:30:25 | 4:16:15 |
| 5:10 − 2:45 | 2:25 |
| 1 h 15 min − 2 h 30 min | -1:15:00 (-1.25 h) |
| 7 h 30 min after 9:45 PM | 5:15 AM, next day |
| 2 h 20 min before 1:10 AM | 10:50 PM, previous day |
| 36 hours after Thu, Sep 24, 2026, 9:00 AM | Fri, Sep 25, 2026, 9:00 PM |
What you can type
Type times the way you would say them. Each row shows how it was read, so you can check it.
| You type | Read as |
|---|---|
2:45 | 2 hours 45 minutes (h:mm) |
1:02:03 | 1 hour 2 minutes 3 seconds (h:mm:ss) |
1:02:03:04 | 1 day 2 hours 3 minutes 4 seconds |
2h 45m, 2 hrs 45 mins, 2h45 | 2 hours 45 minutes |
90m, 90 min | 1 hour 30 minutes |
1.5h | 1 hour 30 minutes |
4m 32s | 4 minutes 32 seconds |
1d 3h, 2 days, 1 week | days and weeks |
3 | 3 hours (or minutes or seconds, you choose) |
A value with one colon, like 4:32, always means hours and minutes. For minutes and seconds, type 4m 32s or 0:04:32. Start a value with a minus sign, such as -15m, to take it away on a + row.
Other time tools
- Hours calculator: the hours and minutes between two times, such as 8:30 AM to 5:15 PM.
- Time card calculator: add up a week of work shifts with breaks, overtime and pay.
- Minutes to decimal: convert minutes to decimal hours for payroll.
Frequently asked questions
How do you add hours and minutes?
Add the hours and the minutes separately, then turn every 60 minutes into 1 hour. For 2 h 45 min + 3 h 30 min: 5 hours and 75 minutes, and 75 minutes is 1 hour 15 minutes, so the total is 6 h 15 min (6:15). In the calculator, type each time on its own row, for example 2:45 and 3:30.
How do you subtract time?
Subtract the minutes first. If there are not enough minutes, borrow 1 hour and add 60 to the minutes. For 5:10 − 2:45, borrow an hour: 4:70 − 2:45 = 2:25. In the calculator, tap the + button next to a row to switch it to −.
How do I add hours, minutes and seconds?
Work from the smallest unit up, carrying 60 each time. 1:25:40 + 0:48:35 + 2:10:50: the seconds add up to 125, which is 2 minutes 5 seconds; the minutes to 25 + 48 + 10 + 2 = 85, which is 1 hour 25 minutes; the hours to 1 + 2 + 1 = 4. The total is 4:25:05. Type h:mm:ss values like 1:25:40 straight into the calculator.
What time will it be in 8 hours?
Add the hours to the current time. At 3:30 PM, 8 hours from now is 11:30 PM. Choose "Time from a start time", tap Now to fill in the current time and date, and type the hours and minutes you want to add. If the result goes past midnight, the calculator shows "+1 day".
What time was it 5 hours ago?
Subtract the hours from the current time, going back past midnight if you need to. 5 hours before 2:00 AM is 9:00 PM the previous day. Choose "Time from a start time", pick "Subtract (before)" and type the duration.
What happens when the time goes past midnight?
The clock rolls over and the day changes. 7 hours 30 minutes after 9:45 PM is 5:15 AM the next day, and 2 hours 20 minutes before 1:10 AM is 10:50 PM the previous day. The calculator labels these "+1 day" and "-1 day"; add a start date to see the exact date.
How do I add minutes and seconds, like lap or song times?
Type them with units, such as 4m 32s, or in h:mm:ss form, such as 0:04:32. A value like 4:32 is read as 4 hours 32 minutes, the usual way to write time. 4 min 32 s + 5 min 7 s = 9 min 39 s. You can also set plain numbers to mean seconds and type 272.
Can the result be negative?
Yes. If you subtract more than you added, the total is shown with a minus sign. 1 h 15 min − 2 h 30 min = -1:15:00, or -1.25 hours.
How do I convert the total to decimal hours?
Divide the minutes by 60 and add them to the hours. 5 h 25 min = 5 + 25 ÷ 60 = 5.4167 hours. The calculator shows every total in decimal hours, total minutes and total seconds as well as h:mm:ss.
How do I find the hours between two times?
That is a different calculation: end time minus start time. Use the hours calculator for the time between two clock times, or the time card calculator to add up a week of work shifts with breaks.
Does the calculator adjust for daylight saving time or time zones?
No. It does clock arithmetic, so 6 hours after 10:00 PM is always 4:00 AM, even on the night the clocks change. If a daylight saving change falls inside your time span, add or subtract that hour yourself.