The basic method: convert everything to minutes first
The simplest way to add hours and minutes is to turn everything into minutes, add them together, then convert back to hours and minutes if you need to. This works because minutes are a single unit — you do not have to think about carrying or borrowing the way you do when you add hours and minutes separately.
Here is the process: multiply each hour by 60 to get minutes, add those minutes to any loose minutes you already have, then add all the minutes together. Once you have your total, divide by 60 to find how many hours that is, and whatever is left over is your remaining minutes.
For example, if you need to add 2 hours 45 minutes plus 1 hour 30 minutes: convert 2 hours to 120 minutes, add the 45 minutes to get 165 minutes. Convert 1 hour to 60 minutes, add the 30 minutes to get 90 minutes. Now add 165 plus 90 to get 255 minutes total. Divide 255 by 60 and you get 4 hours with 15 minutes left over — so 4 hours 15 minutes.
Key Takeaways
- Converting to minutes first removes the need to carry between hours and minutes, making the math simpler and faster.
- Multiply hours by 60, add any loose minutes, then add all the minutes together before converting back to hours and minutes.
- You can also add hours and minutes in columns if you keep minutes in their own column and carry groups of 60 minutes over to the hours column.
- A calculator that handles time (not just numbers) will do the carrying automatically and show you the answer in hours and minutes format.
- The column method works well on paper; the minutes-first method works well in your head.
Adding in columns: the way you learned in school
If you prefer to write it out, you can add hours and minutes the same way you add regular numbers — in columns, with hours on the left and minutes on the right. Write the first time on top, the second time below it, and add straight down.
The catch is that minutes only go up to 59. If your minutes column adds up to 60 or more, you have to carry the extra into the hours column. For example, if the minutes add up to 87, that is 1 hour and 27 minutes, so you write 27 in the minutes column and carry 1 to the hours column.
Here is a concrete example written out:
| Hours | Minutes |
| 3 | 45 |
| + 2 | + 30 |
| 5 | 75 |
| 6 | 15 |
The minutes add to 75. Since 75 is more than 60, subtract 60 from 75 to get 15, and add 1 to the hours column. Your answer is 6 hours 15 minutes.
When to use a time calculator instead
If you are adding more than two times, or if you are adding times repeatedly throughout the day, a calculator designed for time will save you from doing the carrying by hand. These calculators let you type in hours and minutes in the format they are already in, and they return the answer in hours and minutes without you having to convert.
Many online time calculators also let you add seconds, which is useful if you are tracking workout times, video lengths, or work hours that include partial minutes. Some will even subtract time or multiply time by a number — for instance, if you need to know how long five 45-minute meetings take back-to-back.
A spreadsheet program like Excel or Google Sheets can also add time if you format the cells as time and use the SUM function, though this requires a bit of setup the first time. Once it is set up, you can add as many times as you want without thinking about carrying.
Common mistakes and how to avoid them
The most common mistake is forgetting that minutes go from 0 to 59, not 0 to 100. If you add 30 minutes plus 40 minutes and get 70, you cannot just write 70 — you have to convert that to 1 hour 10 minutes. This is where the carrying step matters.
Another mistake is mixing up the conversion. Remember: 1 hour equals 60 minutes, not 100. If you are converting hours to minutes, multiply by 60. If you are converting minutes to hours, divide by 60. Doing it backwards will give you a completely wrong answer.
If you are adding times by hand and lose track of whether you have already carried, write the carry number above the hours column in small writing so you do not forget to add it in.
Adding times with seconds included
If your times include seconds, the process is the same but with an extra column. Seconds go from 0 to 59, just like minutes. Add seconds first, carry groups of 60 seconds to the minutes column, then add minutes and carry groups of 60 minutes to the hours column.
For example, 2 hours 30 minutes 45 seconds plus 1 hour 20 minutes 30 seconds: add the seconds (45 + 30 = 75 seconds, which is 1 minute 15 seconds), add the minutes with the carry (30 + 20 + 1 = 51 minutes), add the hours (2 + 1 = 3 hours). Your answer is 3 hours 51 minutes 15 seconds.
If you are working with seconds regularly, a time calculator becomes even more useful because carrying seconds by hand is tedious and straightforward to mess up.
Using a spreadsheet to add many times at once
If you have a list of times to add — say, daily work hours for a week, or multiple video clips you want to combine — a spreadsheet is faster than adding them one pair at a time.
In Google Sheets or Excel, enter each time in its own cell in the format hours:minutes (or hours:minutes:seconds). Then use the SUM function to add them all at once. The spreadsheet will handle the carrying automatically and show you the total in hours and minutes format.
Make sure the cells are formatted as time before you enter the numbers, or the spreadsheet may treat them as regular numbers and give you a wrong answer. Most spreadsheets have a Format menu where you can set the cell format to Time.
Frequently Asked Questions
What do I do if my minutes add up to more than 60?
Divide the total minutes by 60. The whole number is the hours to carry over, and the remainder is the minutes you write down. For example, 87 minutes is 1 hour and 27 minutes, so you carry 1 to the hours column and write 27 in the minutes column.
Can I add hours and minutes on a regular calculator?
A regular number calculator will not work because it treats 1 hour 30 minutes as the number 1.30, not as 90 minutes. You need either a time calculator, a spreadsheet set to time format, or you need to convert to minutes first, add, then convert back.
How do I add times if some are in 12-hour format and some are in 24-hour format?
Convert everything to 24-hour format first, then add. For example, 2:30 PM is 14:30 in 24-hour format. Once everything is in the same format, the addition works the same way.
What if I need to add times across midnight?
If you are adding 11 PM plus 2 hours, the math is the same (11 + 2 = 13 hours), but 13 hours in 24-hour format is 1 AM the next day. If you need to track which day the time falls on, note that separately — the addition itself does not change.
Is there a keyboard shortcut to add times in Excel?
No keyboard shortcut exists, but once you have entered your times in cells and formatted them as time, typing =SUM(A1:A5) will add cells A1 through A5. Press Enter and Excel shows the total in hours and minutes format.