How to Add Hours and Minutes

How to add hours and minutes by hand

Write the times in two columns, hours on the left and minutes on the right, the way you would line up numbers for column addition.

1. Add the minutes column.
2. Divide the minutes total by 60. The whole number is the carry, and the remainder stays as minutes.
3. Add the hours column plus the carry.

For 3:50 + 2:25 + 1:40, the minutes add to 50 + 25 + 40 = 115. That is 1 hour with 55 minutes left, so 1 is carried. The hours add to 3 + 2 + 1 = 6, plus the carry makes 7, and the total is 7 hours 55 minutes.

Worked examples with the carry

The carry is the minutes total divided by 60, rounded down. A minutes column of 150 holds two full hours (120 minutes) with 30 left over, so it carries 2.

Times added	Hours column	Minutes column	Carry	Total	Decimal hours
2:45 + 1:30	3	75	1	4:15	4.25
3:20 + 4:25	7	45	0	7:45	7.75
0:50 + 0:50 + 0:50	0	150	2	2:30	2.50
6:35 + 2:40 + 1:55	9	130	2	11:10	11.17
7:45 + 8:30 + 7:50 + 8:15 + 6:40	36	180	3	39:00	39.00

The last row is a five-day work week. Its total stays 39:00, because a sum of hours worked does not wrap at 24 the way a clock does.

Adding hours, minutes and seconds

Carry from right to left: every 60 seconds becomes 1 minute, then every 60 minutes becomes 1 hour. Two race splits of 0:48:37 and 0:51:46 add to 83 seconds, which is 1 minute 23 seconds. The minutes then add to 48 + 51 + 1 = 100, which is 1 hour 40 minutes, and the finish time is 1:40:23.

Lap times, race splits and video lengths are all written in this h:mm:ss form. The average of several lap times starts from the same carried total, divided by the number of laps.

Adding a duration to a clock time

Add on the 24-hour clock, then subtract 24 hours if the result reaches 24:00 or more, because the time has passed midnight.

• 10:15 AM plus 2 hours 50 minutes is 10:15 + 2:50 = 12:65, which carries to 13:05, or 1:05 PM.
• 9:40 PM plus 3 hours 35 minutes is 21:40 + 3:35 = 24:75, which carries to 25:15. Taking off 24 hours leaves 1:15 AM the next day.
• 6:30 PM plus 8 hours is 18:30 + 8:00 = 26:30, which is 2:30 AM the next day.

Only the clock-time answer wraps at midnight. A night when the clocks change adds one more twist: 8 hours of real time after 10:00 PM ends at 7:00 AM on the March change night and at 5:00 AM on the November one.

Subtracting hours and minutes

Subtraction runs the carry backward. When the top minutes are smaller than the bottom minutes, borrow 1 hour and add 60 to the top minutes. For 6:05 − 3:50, 5 is smaller than 50, so 6:05 becomes 5:65, and 5:65 − 3:50 = 2:15.

Clock times that cross midnight need one extra step, adding 24 hours to the end time, which the guide on subtracting clock times walks through.

Totaling a time sheet in decimal hours

Add the days in hours and minutes with the carry, and convert the weekly total to decimal hours once at the end. 39:00 is 39.00 hours, and 11:10 is 11 + 10 ÷ 60 = 11.17 hours. An hourly rate multiplies the decimal: 4:15 is 4.25 hours, which pays $76.50 at $18.00 an hour. A time card calculator does the whole sum from in and out punches, with breaks, overtime and pay.

Converting each day to a rounded decimal before adding can drift from the true total by a few hundredths of an hour. The minutes to decimal chart covers single values, and the time card math guide shows that drift on a real week.

Adding time in Excel or Google Sheets

Type each duration as h:mm, such as 7:45, and add the cells with =SUM(A2:A6). The total needs the custom number format [h]:mm. With the plain h:mm format, Excel drops whole days from the display, so the 39:00 week shows as 15:00. In Google Sheets, Format, Number, Duration shows the full total.

Task	Formula	Example result
Total a column of durations	=SUM(A2:A6) with [h]:mm	39:00
Total as decimal hours	=SUM(A2:A6)*24	39
Add 90 minutes to a time in A2	=A2+TIME(0,90,0)	10:15 AM becomes 11:45 AM
Add 30 hours to a time in A2	=A2+30/24	10:15 AM becomes 4:15 PM the next day

TIME wraps at 24 hours, so a span of a day or more has to be added as a fraction of a day, as in the last row.

Common mistakes when adding time

• Typing times into a calculator as decimals gives 2.45 + 1.30 = 3.75. The real total of 2:45 + 1:30 is 4 hours 15 minutes, which is 4.25 decimal hours, not 3.75.
• Forgetting the carry leaves totals like 3:75, which no clock or time sheet accepts.
• Mixing formats, such as adding 7.75 to 8:30, produces a number that means nothing. Convert every entry to the same format first.
• Leaving a spreadsheet total in h:mm hides every full day, so a 39-hour week reads as 15 hours.

Time Addition Calculator