Time Calculator
Calculate your Add/subtract time in seconds with the free Time Calculator. No registration needed.
Two durations
Result
What is a Time Calculator?
A Time Calculator lets you add or subtract hours, minutes, and seconds between two time durations. Enter the hours, minutes, and seconds for duration A, choose whether to add or subtract, then enter duration B. The calculator returns the total in hours, minutes, and seconds, along with the total in each unit individually. People use time calculators to sum up work shifts, calculate total travel itineraries, combine cooking times for recipes, add up music or video runtimes, or figure out time sheet totals. Instead of manually adding 60-minute hours and 60-second minutes in your head, the calculator does all the base-60 arithmetic instantly and correctly.
How to add and subtract time manually (the formula)
To add or subtract time manually, work with each unit from smallest to largest, carrying or borrowing as needed. First convert everything to a common unit like seconds: Total Seconds = (Hours A × 3600) + (Minutes A × 60) + Seconds A, and similarly for Duration B. Then add or subtract: Result Seconds = Total A ± Total B. Finally, convert back: Hours = floor(Result Seconds / 3600), Minutes = floor((Result Seconds % 3600) / 60), Seconds = Result Seconds % 60. For example, to add 2 hours 45 minutes to 1 hour 30 minutes: convert to seconds (2 × 3600 + 45 × 60 = 9,900 seconds, and 1 × 3600 + 30 × 60 = 5,400 seconds), add (15,300 seconds), then convert back: 15,300 / 3600 = 4 hours, remainder 900 / 60 = 15 minutes, giving 4 hours 15 minutes.
Example calculation
Suppose you want to add 3 hours 50 minutes 30 seconds to 1 hour 20 minutes 45 seconds. Enter Duration A as hours = 3, minutes = 50, seconds = 30. Set operation to Add. Enter Duration B as hours = 1, minutes = 20, seconds = 45. Click Calculate. First convert to seconds: Duration A = 3 × 3600 + 50 × 60 + 30 = 10,800 + 3,000 + 30 = 13,830 seconds. Duration B = 1 × 3600 + 20 × 60 + 45 = 3,600 + 1,200 + 45 = 4,845 seconds. Total = 13,830 + 4,845 = 18,675 seconds. Convert back: 18,675 ÷ 3600 = 5 hours (with remainder 675 seconds), 675 ÷ 60 = 11 minutes (with remainder 15 seconds). Result: 5 hours 11 minutes 15 seconds. Total hours = 5.1875, total minutes = 311.25, total seconds = 18,675.
Common mistakes
- Forgetting that time is base-60 — Adding 45 minutes and 30 minutes gives 75 minutes, which is 1 hour 15 minutes, not 1.75 hours displayed as 1 hour 75 minutes.
- Not carrying over extra minutes — When seconds exceed 59, they must be converted to minutes. When minutes exceed 59, they must be converted to hours.
- Negative results without indication — Subtracting a larger duration from a smaller one produces a negative time. The calculator shows a minus sign to make this clear.
- Confusing 12-hour and 24-hour formats — This calculator works with durations (quantities of time), not clock times. Use the Time Duration Calculator for clock time differences.
- Mixing decimal hours with hours and minutes — Entering 2.5 in the hours field means 2 hours and 30 minutes, but entering 2 in hours and 50 in minutes means 2 hours 50 minutes. Be consistent.
Frequently asked questions
How do I add or subtract hours, minutes, and seconds?
Enter the hours, minutes, and seconds for the first duration, choose Add or Subtract, then enter the hours, minutes, and seconds for the second duration. The calculator returns the combined or subtracted time.
Can I add two time durations together?
Yes, select Add and enter both durations. The calculator adds them and returns the total in hours, minutes, and seconds, plus totals in hours, minutes, and seconds separately.
What happens if the result goes over 24 hours?
The calculator handles results over 24 hours correctly. It shows the total in hours, minutes, and seconds without wrapping to days, so you can see durations like 50 hours.
How do I subtract one time from another?
Select Subtract, enter the first duration and then the second. The calculator subtracts the second from the first and shows the difference. If the result is negative, it displays with a minus sign.
Can I use decimal hours as input?
The calculator works with whole hours, minutes, and seconds. For decimal hours (like 2.5 hours), convert to 2 hours and 30 minutes before entering.
What's the difference between this and a time duration calculator?
This calculator adds or subtracts time durations (like 2 hours + 1.5 hours). A time duration calculator finds the span between two clock times (like 9 AM to 5 PM).