Time Calculator

What this calculator does

The Time Calculator has two modes. Add or subtract time combines two durations made of days, hours, minutes, and seconds. Convert time units changes a single value from seconds, minutes, hours, days, or weeks into all of the other units at once.

The add and subtract mode is useful for totaling work logs, media runtimes, travel schedules, or any set of durations where the individual fields may exceed their usual ranges. The conversion mode is a quick reference for project planning, scientific work, and everyday scheduling.

How to use this calculator

1. Choose Add or subtract time or Convert time units.
2. In add mode, fill in the days, hours, minutes, and seconds for the first duration, choose Add or Subtract, then fill in the second duration.
3. In conversion mode, enter a value and choose its current unit.
4. Click Calculate.

The default add example is 1 day 2 hours 3 minutes 4 seconds plus 4 hours and 5 seconds. The result is 1 day 6 hours 3 minutes 9 seconds, or 108,189 total seconds.

Time formulas

Total seconds = days × 86,400 + hours × 3,600 + minutes × 60 + seconds
Result = first total ± second total
Days = floor(total / 86,400)
Hours = floor((total mod 86,400) / 3,600)
Minutes = floor((total mod 3,600) / 60)
Seconds = total mod 60

Unit conversion uses the same base unit:

1 minute = 60 seconds
1 hour = 3,600 seconds
1 day = 86,400 seconds
1 week = 604,800 seconds

Months and years are deliberately excluded from conversion because their lengths vary. A month can contain 28 to 31 days, and a year can contain 365 or 366.

What the results mean

The result is shown both in a compact day-hour-minute-second format and as a total number of seconds. Each input field is independent, so entering 90 minutes is valid and is normalized to 1 hour 30 minutes. If the second duration is larger than the first in subtract mode, the result is negative and the headline keeps a minus sign.

In conversion mode, the result panel lists the value in every supported unit. Decimal results are rounded for display, but the underlying conversion uses the exact unit ratios above.

Assumptions and limitations

• All inputs must be non-negative whole numbers.
• Hours, minutes, and seconds do not need to be below their conventional limits; they are normalized.
• The calculator works with durations, not clock times or calendar dates.
• Months and years are not converted because they are not fixed-length units.
• Results are displayed with up to six decimal places.

Frequently asked questions

Can I enter 90 minutes instead of 1 hour 30 minutes?

Yes. Each field is normalized, so 90 minutes becomes 1 hour and 30 minutes in the result. The same applies to hours and seconds.

Why is the result negative?

A negative result appears in subtract mode when the second duration is larger than the first. The absolute day, hour, minute, and second values are still shown so you can read the size of the difference.

Why are months and years missing from the converter?

Months and years do not have a single fixed length. Converting them with an average would produce misleading results for scheduling and payroll, so the converter stays with exact units.

Reference tables

Time units

Unit definitions

Source

Reference: Calculator.net — Time Calculator.