Adding hours and minutes
Time is base 60, so adding hours and minutes is not the same as adding decimals. Add the minutes column and the hours column separately, then carry every full 60 minutes into the hours.
Example: 7:45 + 8:30 + 6:50
- Hours: 7 + 8 + 6 = 21.
- Minutes: 45 + 30 + 50 = 125.
- Carry: 125 minutes = 2 hours 5 minutes.
- Result: 21 + 2 = 23 hours, 5 minutes, written 23:05.
In decimal the same sum is 7.75 + 8.50 + 6.83 = 23.08, which agrees with 23:05 (5 ÷ 60 = 0.08). If you have many entries, convert everything to minutes first: 465 + 510 + 410 = 1,385 minutes; 1,385 ÷ 60 = 23 remainder 5, so 23:05 again. The minutes method never produces a carry error.
Totals can exceed 24 hours. A week of 8:15, 8:40, 7:50, 9:05 and 8:10 is 42:00, not 1 day 18 hours. The calculator keeps hours as a running count unless you ask for days.
Subtracting hours and minutes
Subtract the minutes first. If the top minutes are smaller than the bottom minutes, borrow 60 minutes from the hours.
Example: 9:20 − 3:45
- Minutes: 20 − 45 is negative, so borrow: 9:20 becomes 8:80.
- Minutes: 80 − 45 = 35.
- Hours: 8 − 3 = 5.
- Result: 5:35.
Subtraction is how a single shift is measured: clock-out minus clock-in. 5:40 PM minus 8:15 AM is 17:40 − 08:15 in 24-hour time = 9:25. For durations that cross midnight, add 24 hours to the end time first; the time duration calculator does this automatically.
Subtracting a break from a duration works the same way: 9:25 − 0:45 = 8:40. The result is 8 hours 40 minutes, and the decimal equivalent is 8.67, not 8.40.
Hours to minutes and back
Hours to minutes: multiply by 60. Minutes to hours: divide by 60; the whole number is the hours and the remainder is the minutes.
| Hours and minutes | Total minutes | Decimal hours |
|---|---|---|
| 0:15 | 15 | 0.25 |
| 0:30 | 30 | 0.50 |
| 0:45 | 45 | 0.75 |
| 1:00 | 60 | 1.00 |
| 1:30 | 90 | 1.50 |
| 2:00 | 120 | 2.00 |
| 2:45 | 165 | 2.75 |
| 4:00 | 240 | 4.00 |
| 7:30 | 450 | 7.50 |
| 8:00 | 480 | 8.00 |
| 8:20 | 500 | 8.33 |
| 10:00 | 600 | 10.00 |
| 12:00 | 720 | 12.00 |
| 24:00 | 1,440 | 24.00 |
| 40:00 | 2,400 | 40.00 |
Example: 500 minutes ÷ 60 = 8.33, and 8 × 60 = 480, leaving 20 minutes, so 500 minutes is 8:20.
Decimal hours versus hh:mm
The colon format shows hours and minutes as two numbers in base 60. Decimal hours show one number in base 10. Payroll, invoicing and spreadsheets that multiply time by a rate need decimal hours, because 8:20 cannot be multiplied by $20 directly but 8.33 can.
The conversion is minutes ÷ 60. It is exact only for 15, 30 and 45 minutes; every other value is rounded, usually to two decimals. The practical consequence is that you should add times in hh:mm (or in whole minutes) and convert the final total once. Converting each entry and adding the rounded decimals can differ by a few hundredths. The minutes to decimal chart lists all 60 values with two and three decimals.
A common error is reading 8.30 as 8 hours 30 minutes. 8.30 is 8 hours 18 minutes; 8 hours 30 minutes is 8.50.
What people use an hours calculator for
- Weekly work totals. Add the daily hours from a time card and check the result against the pay stub.
- Drive time and logbooks. Add legs of 2:35, 1:50 and 3:10 to get 7:35 of driving.
- Study or training hours. Programs that require a number of contact hours are usually tracked in hh:mm and reported in decimal.
- Billable time. Freelancers add session times across a project and multiply the decimal total by the hourly rate.
- Remaining time. Subtract hours already worked from the contracted weekly hours to see what is left: 37:30 − 29:45 = 7:45.
- Durations longer than a day. Add shifts across a month and keep the result in hours, for example 168:20, rather than converting to days.
Frequently asked questions
How do I add hours and minutes?
Add the hours and the minutes separately, then convert every 60 minutes into one hour. 7:45 + 8:30 + 6:50 gives 21 hours and 125 minutes; 125 minutes is 2 hours 5 minutes, so the total is 23:05. Alternatively, convert each time to minutes, add them and divide the sum by 60.
How do I subtract time?
Subtract minutes first. If the minutes you are subtracting are larger, borrow one hour as 60 minutes. 9:20 minus 3:45: borrow to make 8:80, then 80 minus 45 is 35 minutes and 8 minus 3 is 5 hours, so the answer is 5:35. For clock times that cross midnight, add 24 hours to the later time before subtracting.
What is 7.5 hours in hours and minutes?
7.5 hours is 7 hours 30 minutes, because 0.5 times 60 is 30 minutes. The same rule works for any decimal: multiply the fractional part by 60. 7.25 is 7:15, 7.75 is 7:45 and 7.33 is about 7:20. Note that 7.30 in decimal is 7 hours 18 minutes, not 7 hours 30 minutes.
How many minutes are in 8 hours?
8 hours is 480 minutes, since 8 times 60 is 480. To go the other way, divide minutes by 60: 500 minutes is 8 hours with 20 minutes left over, written 8:20 or 8.33 in decimal. A 40-hour week is 2,400 minutes.
Can the calculator add more than 24 hours?
Yes. Totals are kept as a running count of hours, so a week can show 42:15 and a month 170:40. Nothing is converted into days unless you ask for it. This matters for timesheets, where 42:15 is what payroll needs, not 1 day 18 hours 15 minutes.
Should I add decimal hours or hh:mm?
Add in hh:mm or whole minutes and convert the total to decimal once at the end. Decimal values are rounded except for quarter hours, so adding several rounded figures can be off by a few hundredths. Five entries of 7:50 total 39:10, which is 39.17; adding five rounded 7.83 values gives 39.15.
What is the difference between an hours calculator and a time card calculator?
An hours calculator adds or subtracts durations you already know, such as 7:45 and 8:30. A time card calculator starts from clock-in and clock-out times, deducts breaks, works out the duration of each day and applies overtime rules for a pay period. Use this page for arithmetic on durations and the time card for punches.
Related calculators
- Work Hours CalculatorEnter your start time, end time and unpaid breaks to get hours worked for a day, a week or a pay period in hh:mm and decimal hours. Overnight shifts, overtime and pay are handled automatically.
- Time Duration Calculator: Hours Between Two TimesEnter a start time and an end time, with dates if the span is longer than a day, to get the elapsed time in hours and minutes, total minutes and decimal hours.
- Hours to Decimal Calculator and Minutes to Decimal ChartEnter a time in hours and minutes to get decimal hours, or enter decimal hours to get hours and minutes. The chart below lists every minute from 1 to 60.
- Time Card Calculator with Lunch and OvertimeFill in clock-in, clock-out and lunch for each day of a weekly or biweekly pay period. The time card totals hours in hh:mm and decimal, splits regular and overtime hours, and can be printed or exported.