Scheduling

Time Duration Calculator

Enter time segments in hours, minutes, and seconds to get one total duration. The calculator handles rollover from seconds to minutes and minutes to hours, useful for work logs, media lengths, workouts, and schedules.

Last reviewed May 14, 2026 by ToolSpilo Editorial Team.

Review method: Reviewed against standard base-60 time-duration arithmetic; weak generic content was replaced with rollover, decimal-hour, and payroll caveats.

Calculator tool

How this calculator works

Use the explanation to understand the formula, assumptions, and practical limits behind the calculator result.

What This Calculator Adds

A time duration calculator adds separate time segments into one total. It works with durations, not clock times. That means 1 hour 30 minutes + 45 minutes = 2 hours 15 minutes, regardless of the time of day.

Rollover Rules

60 seconds=1 minute60 \text{ seconds} = 1 \text{ minute}
60 minutes=1 hour60 \text{ minutes} = 1 \text{ hour}

Worked Example

Segments:

  • 1:25:40
  • 0:48:35
  • 2:10:50

Add seconds: 40+35+50=12540 + 35 + 50 = 125 seconds = 2 minutes 5 seconds.

Add minutes: 25+48+10+2=8525 + 48 + 10 + 2 = 85 minutes = 1 hour 25 minutes.

Add hours: 1+0+2+1=41 + 0 + 2 + 1 = 4 hours.

Total: 4:25:05.

Decimal Hours

Payroll and billing often use decimal hours. Convert minutes by dividing by 60:

Decimal hours=hours+minutes60+seconds3600\text{Decimal hours} = \text{hours} + \frac{\text{minutes}}{60} + \frac{\text{seconds}}{3600}

Example: 2:30:00 = 2+30/60=2.52 + 30/60 = 2.5 hours.

Frequently asked questions

Is this the same as subtracting clock times?

No. This calculator adds durations. Clock-time subtraction needs a start time, end time, date, and sometimes a time zone.

Example: 11:00 PM to 1:00 AM crosses midnight, so clock subtraction needs the date. A duration like 2 hours does not.

How do I convert minutes to decimal hours for billing?

Divide minutes by 60.

Examples:

  • 15 minutes = 15/60=0.2515/60 = 0.25 hours
  • 30 minutes = 30/60=0.5030/60 = 0.50 hours
  • 45 minutes = 45/60=0.7545/60 = 0.75 hours

For seconds, divide by 3600.

Why does 90 minutes show as 1 hour 30 minutes?

Because time rolls over at 60, not 100. When minutes reach 60, they become one hour.

That is why 1.5 hours means 1 hour 30 minutes, not 1 hour 50 minutes.

Can I use this for payroll?

Use it to total durations, then check your payroll rounding rules. Employers may round to 5, 6, 10, or 15 minute increments depending on policy and law.

For formal payroll, keep the original time records and use the required rounding method.