# Time Calculator

> To add times, add the hours, minutes and seconds separately and carry each 60: 3 h 40 min + 2 h 35 min = 5 h 75 min = 6 h 15 min, or 6.25 decimal hours. You can also subtract durations or add time to a clock time, such as 9:50 PM + 2 h 35 min = 12:25 AM the next day.

- Interactive calculator: https://calculatorswithsteps.com/time-calculator
- Category: Date & Time Calculators
- Last updated: 2026-11-10
- Publisher: Calculators With Steps (calculatorswithsteps.com)

## How to use the time calculator

Choose what you want to do:

- **Two durations** combines two lengths of time, A and B. Use it to total the hours on a project, add up lap times or find the difference between two durations.
- **A clock time** starts from a time of day, such as 21:50, and moves it forward or back by duration B. The result tells you if it lands on the next or previous day.

Fill in only the units you need. Blank boxes count as zero, and decimals are fine: 1.5 hours means 1 hour 30 minutes. The result shows h:mm:ss, a written-out version, and the same total in decimal hours, minutes and seconds.

## How adding and subtracting time works

Time is counted in base 60 for minutes and seconds, then base 24 for hours in a day. That is why you can't add 3:40 and 2:35 like ordinary decimals. The reliable method is to convert everything to one unit, do the sum, and convert back:

**Total seconds = days × 86,400 + hours × 3,600 + minutes × 60 + seconds**

After adding or subtracting, divide by 3,600 for whole hours, divide the remainder by 60 for minutes, and what is left is seconds. For a clock time, divide by 86,400 to see how many days you have crossed and keep the remainder as the time of day.

## Worked examples

| Calculation | Result | Decimal hours |
| --- | --- | --- |
| 3 h 40 min + 2 h 35 min | 6:15:00 | 6.25 |
| 7 h 45 min + 8 h 30 min | 16:15:00 | 16.25 |
| 1.5 h + 45 min | 2:15:00 | 2.25 |
| 1 day 20 h 30 min + 5 h 45 min 30 s | 50:15:30 | 50.2583 |
| 1 h 15 min − 2 h | −0:45:00 | −0.75 |

The first example step by step: A is 13,200 seconds and B is 9,300 seconds. Together that is 22,500 seconds. 22,500 ÷ 3,600 = 6 hours with 900 seconds left over, and 900 ÷ 60 = 15 minutes.

## Converting minutes to decimal hours

Time sheets and payroll systems often want decimal hours. Divide the minutes by 60:

| Minutes | Decimal hours |
| --- | --- |
| 5 | 0.0833 |
| 10 | 0.1667 |
| 15 | 0.25 |
| 20 | 0.3333 |
| 30 | 0.5 |
| 40 | 0.6667 |
| 45 | 0.75 |
| 50 | 0.8333 |

A common slip is writing 7 h 45 min as 7.45 hours. It is 7.75 hours. Paying 7.45 instead would short someone 18 minutes. To total a whole work week with breaks, the [hours calculator](https://calculatorswithsteps.com/hours-calculator) does this conversion for each shift.

## Adding time to a clock and crossing midnight

In clock mode, the calculator works in 24-hour time and also shows the 12-hour version. When the sum goes past 24:00 it subtracts a day and labels the result "+1 day". When a subtraction goes below 00:00 it adds a day and labels it "−1 day".

| Start | Change | Result |
| --- | --- | --- |
| 21:50 (9:50 PM) | + 2 h 35 min | 00:25 (12:25 AM), next day |
| 01:30 (1:30 AM) | − 3 h 45 min | 21:45 (9:45 PM), previous day |
| 09:15 (9:15 AM) | + 2 days 3 h | 12:15 (12:15 PM), 2 days later |

Midnight is 00:00 in 24-hour time and 12:00 AM on a 12-hour clock. Noon is 12:00 and 12:00 PM. This is handy for flight arrival times, night shifts, cooking and medication schedules. For whole days rather than hours, use the [date calculator](https://calculatorswithsteps.com/date-calculator).

## Time formulas in Excel and Google Sheets

Spreadsheets store a time as a fraction of a day, so 6:00 is 0.25. A few formulas cover most needs:

- `=A1+B1` adds two times. Format the cell as `[h]:mm:ss`, or totals over 24 hours restart from zero.
- `=B1-A1` gives the time between a start and an end time. Use `=MOD(B1-A1,1)` when the end is after midnight.
- `=A1*24` converts a time to decimal hours, and `=A1*1440` to minutes.
- `=TIME(2,35,0)` builds a duration of 2 h 35 min to add to another time.

## Tips

- Check whether your result is a duration (how long) or a clock time (what time). 25:30 is a valid duration but not a time of day.
- When you subtract a longer time from a shorter one, the calculator shows a minus sign rather than wrapping around.
- For running splits and race targets, the [pace calculator](https://calculatorswithsteps.com/pace-calculator) converts time over a distance into pace per mile or kilometre.

## Frequently asked questions

### How do I add hours and minutes together?

Add the minutes first, turn every 60 minutes into an hour, then add the hours. 3 h 40 min + 2 h 35 min = 5 h 75 min, and 75 minutes is 1 h 15 min, so the total is 6 h 15 min.

### How do I convert minutes to decimal hours?

Divide the minutes by 60. 15 minutes is 0.25 hours, 30 minutes is 0.5 and 45 minutes is 0.75, so 6 hours 15 minutes is 6.25 hours. Payroll and time sheets usually need this decimal form.

### What time is it 2 hours 35 minutes after 9:50 PM?

It is 12:25 AM the next day. In 24-hour time, 21:50 plus 2:35 is 24:25, and taking off one full day of 24 hours leaves 00:25.

### How do I subtract time that crosses midnight?

Borrow a day of 24 hours. 1:30 AM minus 3 hours 45 minutes is 9:45 PM on the previous day, because 25:30 − 3:45 = 21:45.

### How do I add time in Excel?

Enter durations as h:mm, add them with =A1+B1 and format the result cell as [h]:mm so totals above 24 hours don't wrap around. Multiply a time by 24 to turn it into decimal hours.

### What is 1.5 hours in hours and minutes?

1.5 hours is 1 hour 30 minutes, because 0.5 × 60 = 30. Adding 45 minutes to it gives 2 hours 15 minutes, or 2.25 hours.

### What is time and a half?

Time and a half is a pay rate of 1.5 times your normal hourly rate. Under the US Fair Labor Standards Act, non-exempt employees get it for hours over 40 in a workweek. The hours calculator on this site works out the overtime for you.

## Sources

- [Wikipedia – 24-hour clock](https://en.wikipedia.org/wiki/24-hour_clock)
- [Wikipedia – 12-hour clock](https://en.wikipedia.org/wiki/12-hour_clock)
- [Wikipedia – Sexagesimal (base-60) counting](https://en.wikipedia.org/wiki/Sexagesimal)