⏱️ Time Calculator
Add or subtract time durations, calculate the duration between two times, and convert between time units — all in one place.
How It Works
Time Calculation Tips
- 🕐 Enter times in HH:MM:SS format (e.g. 09:05:30). You can omit seconds by entering HH:MM and the calculator will treat seconds as 0.
- 🌙 The Add/Subtract tab handles times past midnight gracefully — if you add 6 hours to 22:00:00, you get 04:00:00 the next day.
- ⚡ For quick mental maths, remember: 1 hour = 3,600 seconds; 1 day = 86,400 seconds; 1 week = 604,800 seconds.
- 🔄 The Unit Converter handles very large or small values — try entering milliseconds from a stopwatch app to see the human-readable breakdown.
Frequently Asked Questions
Use the Add / Subtract tab. Enter your start time in HH:MM:SS format, choose Add, then enter the hours and minutes you want to add. The result is shown in both 12-hour and 24-hour formats with automatic carry-over.
The 12-hour clock uses AM (midnight to noon) and PM (noon to midnight), repeating 1–12 twice daily. The 24-hour clock (military time) runs from 00:00 to 23:59 with no AM/PM ambiguity. For example, 3:00 PM in 12h is 15:00 in 24h.
Time zones are offsets from Coordinated Universal Time (UTC). For example, New York is UTC-5 in winter (EST) and UTC-4 in summer (EDT). When converting between cities, add or subtract the UTC offset difference. The sidebar shows quick reference offsets for major cities.
Use the Time Duration tab. Enter your clock-in time as the start and clock-out time as the end. The result shows exact hours, minutes, and seconds worked along with the total minutes — useful for timesheet calculations.
Divide the minutes by 60. For example, 150 minutes ÷ 60 = 2.5 hours (2 hours 30 minutes). Use the Unit Converter tab for instant conversion of any value across milliseconds, seconds, minutes, hours, days, and weeks.
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