Free Online Time Calculator
Add or subtract hours, minutes, and seconds.
Values are normalized automatically: 90 minutes becomes 1 hour 30 minutes, and clock results wrap past midnight with a day-offset note.
About the Time Calculator
Adding and subtracting time by hand is awkward because the units are not decimal. An hour has 60 minutes, a minute has 60 seconds, and a day has 24 hours, so a column of numbers cannot simply be added like money. This calculator normalizes every value for you and presents the answer as a readable duration, total seconds, and decimal hours.
Two ways to calculate
In duration mode, enter two amounts of time in days, hours, minutes, and seconds, then add or subtract them. This is useful for combining work logs, travel legs, media lengths, or exercise splits. In clock mode, start from a time of day and add or subtract a duration. The result wraps past midnight and reports whether it lands on the next day, the previous day, or several days away.
Normalization and borrowing
Every input is converted to seconds internally. That makes subtraction straightforward even when the second duration is larger than the first: the result simply becomes negative, and the readable output shows a minus sign. When the total is positive, the calculator divides it back into days, hours, minutes, and seconds, so 90 minutes is always shown as 1 hour 30 minutes rather than an oversized minute field.
Decimal hours
Decimal hours are common in timesheets and payroll systems. One hour and 30 minutes is 1.5 decimal hours, while 45 minutes is 0.75. The calculator converts the signed total seconds to hours and rounds to a practical number of decimal places, making it easy to copy the figure into an invoice or spreadsheet.
Frequently asked questions
What happens if I subtract a larger duration?
The answer becomes negative. The readable result keeps the minus sign, and the total-seconds and decimal-hour values are also negative.
Why does 1:45 plus 0:30 show 2:15 rather than 1:75?
Time is normalized to base 60. Seventy-five minutes is rewritten as 1 hour 15 minutes, so the result becomes 2 hours 15 minutes.
Can I add more than 24 hours to a clock time?
Yes. The clock result wraps around midnight and the note tells you how many days before or after the original time the result falls.