Time Calculator
Calculate time duration, add and subtract time with precision. Free online time calculator for work hours, project tracking, and time management.
To calculate time difference: Convert both times to 24-hour format, then subtract. Example: 5:30 PM - 9:00 AM = 17:30 - 09:00 = 8 hours 30 minutes.
This calculator handles duration, adding/subtracting time, and overnight calculations.
Time Conversion Quick Reference
- 1 Hour
- 60 Minutes
- 1 Day
- 24 Hours
- Standard Workday
- 8 Hours
- Work Week
- 40 Hours
or 3,600 seconds
or 1,440 minutes
Typical 9 AM - 5 PM
5 days × 8 hours
Calculation Mode
Calculate Time Duration
About Time Calculator
The Time Calculator helps you perform various time calculations including finding the duration between two times, adding time periods together, or subtracting time. Perfect for calculating work hours, project time tracking, or any time-based calculations.
Use Cases
- Work Hours: Calculate total hours worked between clock-in and clock-out times
- Project Tracking: Track time spent on tasks and projects
- Time Management: Plan schedules and time allocations
- Payroll: Calculate billable hours and overtime
- Travel Time: Determine travel duration and arrival times
- Event Planning: Calculate event duration and scheduling
- Cooking & Baking: Add up preparation and cooking times
- Exercise: Track workout duration and rest periods
How to Use
Time Duration Mode
- Enter your start time (hours, minutes, seconds, AM/PM)
- Enter your end time
- Click "Calculate Duration" to see the time difference
- View results in hours, minutes, seconds, and total conversions
Note: If end time is earlier than start time, the calculator assumes the end time is on the following day.
Add Time Mode
- Enter your base time (hours:minutes:seconds)
- Enter the time you want to add
- Click "Calculate Result" to see the total time
- Result automatically handles overflow (60 minutes = 1 hour, etc.)
Subtract Time Mode
- Enter your base time
- Enter the time you want to subtract
- Click "Calculate Result" to see the remaining time
- Result cannot be negative (minimum is 0:00:00)
Time Conversions
Common Time Calculations
- Standard Work Day: 8 hours (9 AM to 5 PM with 1-hour lunch)
- Full-Time Week: 40 hours (5 days × 8 hours)
- Overtime: Hours worked beyond 40 per week (or 8 per day)
- Break Time: Usually 15 minutes per 4 hours worked
- Lunch Break: Typically 30 minutes to 1 hour (often unpaid)
- Time Zone Difference: Calculate meeting times across zones
Tips for Accurate Calculations
- Use 24-Hour Format: Or carefully select AM/PM to avoid confusion
- Include Breaks: Subtract break time from total work hours
- Round Appropriately: Some employers round to nearest 15 minutes
- Account for Daylight Saving: Spring forward, fall back affects calculations
- Double-Check Input: Verify all times before calculating
- Consider Time Zones: For international calculations, convert to same zone first
Decimal Hours Explanation
Many payroll systems use decimal hours instead of hours:minutes format:
Pro Tip: When calculating work hours, remember to subtract unpaid breaks. For example, if you work 9 AM to 5 PM with a 1-hour unpaid lunch, your total is 7 hours, not 8 hours. Use the subtract mode to deduct break time from your total hours.
Frequently Asked Questions About Time Calculations
How do I calculate time duration between two times?
To calculate time duration, enter your start time and end time in the calculator. The tool converts both times to 24-hour format, then subtracts the start time from end time. For example, from 9:00 AM to 5:30 PM equals 8 hours and 30 minutes. If the end time is earlier than start time, the calculator assumes overnight calculation.
How do I add time together?
To add time, use the 'Add Time' mode. Enter your base time (e.g., 2 hours 30 minutes) and the time to add (e.g., 1 hour 45 minutes). The calculator automatically handles overflow, so 2:30 + 1:45 = 4:15 (4 hours and 15 minutes).
What is the formula for calculating time difference?
Time difference formula: Convert both times to total seconds (hours×3600 + minutes×60 + seconds), then subtract: End Time Seconds - Start Time Seconds = Duration in Seconds. Convert back by dividing: hours = seconds ÷ 3600, remaining minutes = (seconds mod 3600) ÷ 60.
How do I calculate work hours for payroll?
Enter your clock-in time as start time and clock-out time as end time. Remember to subtract unpaid break time. For example: Clock in 9:00 AM, Clock out 5:30 PM = 8.5 hours. Minus 1-hour lunch = 7.5 billable hours. Use decimal format (7.5) for payroll systems.
How do I convert hours and minutes to decimal hours?
Divide minutes by 60 and add to hours. Formula: Decimal Hours = Hours + (Minutes ÷ 60). Examples: 30 minutes = 0.5 hours, 15 minutes = 0.25 hours, 45 minutes = 0.75 hours. So 2 hours 15 minutes = 2.25 decimal hours.
Can I calculate time across midnight?
Yes, our time calculator handles overnight calculations automatically. If your end time is earlier than start time (e.g., start 10:00 PM, end 6:00 AM), the calculator recognizes this as crossing midnight and calculates 8 hours correctly.
Time Duration Formula
Variables:
- End Time = The later time (converted to 24-hour format)
- Start Time = The earlier time (converted to 24-hour format)
- Duration = The resulting time difference in hours:minutes:seconds
Example:
Calculate work hours from 9:00 AM to 5:30 PM
17:30 - 09:00 = 8 hours 30 minutes
Result: 8 hours 30 minutes (or 8.5 decimal hours)
Related Time Calculators
Tips
- Enter the dimensions in the same unit for consistency.
- Results update automatically as you type.
- Use the unit selector to convert between different measurement systems.