Add, subtract, multiply, or divide time in hours, minutes, and seconds. Convert between time formats instantly.
Standard 24-hour clock arithmetic. Times that cross midnight wrap to the next day.
| Start time | Operation | Result | Total seconds | Apply |
|---|---|---|---|---|
| 09:00:00 | + 2h 30m 0s | 11:30:00 | 41,400 | Use this → |
| 14:30:00 | + 0h 45m 0s | 15:15:00 | 54,900 | Use this → |
| 08:15:00 | + 8h 0m 0s | 16:15:00 | 58,500 | Use this → |
| 23:45:00 | + 0h 30m 0s | 00:15:00 (next day) | 900 | Use this → |
| 10:00:00 | − 1h 15m 0s | 08:45:00 | 31,500 | Use this → |
| 06:00:00 | + 12h 30m 0s | 18:30:00 | 66,600 | Use this → |
Conversion: 1 hour = 3,600 seconds; 1 minute = 60 seconds. Use the calculator above for arbitrary operations including multiply and divide.
Cross-checked against authoritative formulas (IRS, NIST, ACSM) and updated for 2025/2026 tax years and rates.
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Estimates only. Calculator results are for educational and planning purposes — not professional advice. For binding decisions on taxes, investments, health, or legal matters, consult a qualified professional.
FAQ
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A time calculator is a free tool that adds, subtracts, multiplies, or divides hours, minutes, and seconds. Our time calculator handles durations beyond 24 hours and converts between hh:mm:ss formats and decimal hours. The time calculator is used for billing, project time tracking, and converting time zones.
How it works
Our time calculator lets you perform arithmetic on hours, minutes, and seconds and convert between time formats.
Type the first time and second time, or a single time for conversion. The time calculator accepts hh:mm:ss format or decimal hours. Toggle the format using the unit selector.
Choose add, subtract, multiply, or divide. The time calculator applies the operation and shows the result in your chosen format. For multiplication, enter a number (e.g. 1.5 for time-and-a-half).
The result shows the answer in hh:mm:ss and decimal hours, plus the total in seconds for easy use in spreadsheets. The time calculator also shows billing amounts if an hourly rate is entered. The share button creates a link with your inputs pre-filled.
Add or subtract hours from a clock time, with break time support.
Calculate total work hours and pay between two times.
Calculate work hours and pay from clock-in times with overtime and break deductions.
Convert time between any two time zones, accounting for DST.
Sponsored
Time calculations help you add or subtract time periods for various applications.
Common Uses:
Time Conversion:
Calculation Tips:
This calculator works with 24-hour time format and handles time arithmetic across day boundaries.
Type start and end times using hours, minutes, and seconds. The calculator accepts both 12-hour (AM/PM) and 24-hour formats.
Choose to add a duration (e.g. 2h 30m) to a starting time, or subtract a duration to find the earlier time. We handle day rollover automatically.
See the answer in hours, minutes, seconds, decimal hours, and total seconds. Perfect for payroll, billing, and time tracking.
For related calculations, try our hours calculator.