Time Adder Calculator - Add or Subtract Hours, Minutes and Seconds
Enter up to five time values, each in days, hours, minutes, and seconds. Choose whether each entry is added or subtracted, and the calculator instantly shows the running total in HH:MM:SS format, broken down by days, hours, minutes, and seconds. The "show your work" panel walks through each step so you can see exactly how the totals carry over.
Formula
Worked example
Add 1d 2h 30m 0s and 3h 45m 0s: (1 × 86400 + 2 × 3600 + 30 × 60) + (3 × 3600 + 45 × 60) = 97200 + 13500 = 110700 s = 30h 45m 0s (1 day 6 hours 45 minutes).
How the time adder works
Each entry converts your days, hours, minutes, and seconds to a single number of seconds. The calculator then adds or subtracts each entry in order, keeping a running total. At the end it converts the grand total back into days, hours, minutes, and seconds for the main display, and also shows the result in HH:MM:SS format, decimal hours, and total seconds. Carry-over is automatic: entering 75 minutes does not cause an error, it simply becomes 1 hour 15 minutes in the final answer.
When to add vs. subtract an entry
Use the Add (+) option when the entry represents time you want to accumulate, for example a shift duration, a project task, or a timer lap. Use Subtract (-) when you want to remove time from the running total, for example to deduct a break, a lunch period, or a correction. The calculator handles the arithmetic; you just choose the sign.
Converting to decimal hours for timesheets
Many payroll and project-management systems expect time in decimal hours rather than hours and minutes. To convert, divide the total number of minutes by 60 (for example, 7 hours 45 minutes = 7 + 45/60 = 7.75 h). This calculator shows that figure automatically in the "Total in hours" output and in the steps panel, so you can copy it directly into a timesheet.
Practical uses
The time adder is useful any time you need to combine durations rather than clock times: totalling the running time of video clips, summing workout segments, tallying work hours across tasks, calculating how long a multi-leg journey takes, or adding up cooking stages for a recipe. Because the inputs accept whole numbers in each unit, there is no need to do any mental conversion before typing.
Time unit conversion reference
| Unit | Equivalent in seconds | Equivalent in minutes | Equivalent in hours |
|---|---|---|---|
| 1 second | 1 s | 0.0167 min | 0.000278 h |
| 1 minute | 60 s | 1 min | 0.0167 h |
| 1 hour | 3,600 s | 60 min | 1 h |
| 1 day | 86,400 s | 1,440 min | 24 h |
| 1 week | 604,800 s | 10,080 min | 168 h |
Standard conversion factors between common time units.
Frequently asked questions
Can I enter more than 60 minutes or 60 seconds?
Yes. You can type any whole number into the minutes or seconds field. The calculator automatically carries the excess over into hours or minutes. For example, entering 90 minutes is the same as entering 1 hour 30 minutes.
How do I subtract time?
Change the operation selector for that entry from "Add (+)" to "Subtract (-)". The entry will be deducted from the running total instead of added. If more time is subtracted than has been added, the result will be negative and shown with a minus sign.
What does the HH:MM:SS format mean when there are more than 24 hours?
In this calculator the hours column is not capped at 23. A result of 30:15:00 means 30 hours and 15 minutes, not 6 hours the next day. This makes the format suitable for totalling work or project hours that span multiple days.
How do I convert the total to decimal hours for a timesheet?
Look at the "Total in hours" output. It shows the grand total expressed as a decimal, for example 6.75 for six hours and forty-five minutes. You can also divide the total minutes by 60 yourself: (hours × 60 + minutes) / 60.
What if I only want to add two entries?
Leave entries 3, 4, and 5 at zero (or blank). The calculator ignores any row where all four fields are zero, so only the non-zero entries count toward the total.