Time Calculator
Add, subtract, multiply and divide time in hours, minutes, seconds and milliseconds. Type your values, pick an operation, and get an instant, accurate result you can copy.
What this calculator does
This time calculator works directly with durations rather than clock times. You enter two amounts of time — or one amount and a number — choose an operation, and it returns a normalised result. "Normalised" means it carries overflow between units the way a clock does: 90 seconds becomes 1 minute 30 seconds, and 70 minutes becomes 1 hour 10 minutes.
It is ideal for timesheets, cooking, workouts, lab timing, audio and video editing, and any task where you need to combine or scale lengths of time without converting everything to seconds by hand.
How to use this calculator
- Pick an operation: Add, Subtract, Multiply or Divide.
- Type your first duration into Time A using any mix of hours, minutes, seconds and milliseconds.
- For add and subtract, enter a second duration in Time B. For multiply and divide, enter a plain number instead.
- Read the normalised result instantly, then press Copy result to use it elsewhere.
Worked examples
1 h 30 min + 0 h 45 min = 2 h 15 min. The minutes total 75, which carries one hour over and leaves 15 minutes.
3 h 10 min − 1 h 25 min = 1 h 45 min. Borrowing one hour turns 10 minutes into 70 before subtracting 25.
0 h 25 min × 3 = 1 h 15 min. Useful for repeated tasks, sets, or batches.
2 h 00 min ÷ 4 = 0 h 30 min. Handy for splitting a total time into equal slots.
Doing it by hand
The reliable manual method is to convert each duration to a single unit, do the arithmetic, then convert back:
- Total seconds =
hours × 3600 + minutes × 60 + seconds + milliseconds ÷ 1000. - Add, subtract, multiply or divide those totals.
- Convert back: hours =
total ÷ 3600(whole part), remaining seconds give minutes and seconds.
The calculator above does exactly this, which is why its answers always agree with a careful pen-and-paper check.
Common use cases
- Timesheets & payroll — total the hours and minutes worked across several entries.
- Cooking & baking — combine prep, rest and bake times to plan when to start.
- Workouts — multiply a single set or interval by the number of rounds.
- Media editing — add clip lengths or split a runtime into equal segments.
- Study & focus blocks — divide an available block into equal sessions.
Frequently asked questions
How does the time calculator add hours and minutes?
Enter values for each operand, choose Add, and the calculator sums every unit and carries the overflow. For example 1 h 50 min plus 0 h 20 min becomes 2 h 10 min, because 70 minutes carries one hour over.
Can I subtract time and get a negative result?
Yes. If the second duration is larger, the result is shown with a minus sign as a normalised duration in hours, minutes and seconds.
Does it support milliseconds?
Yes. Every operation works down to the millisecond, and 1000 milliseconds carry into one second automatically.
How is this different from a time duration calculator?
This tool does arithmetic on durations you type in. A time duration calculator finds the elapsed time between two clock times, such as 9:15 AM to 5:45 PM.