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Time Difference Calculator
Calculate time difference between two times or dates. Find duration in hours, minutes, and seconds. Support for AM/PM format, 24-hour format, and date-time calculations. Perfect for time tracking and scheduling.
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⌨️ Press Enter to calculate, Esc to clear
Free Time Difference Calculator
Calculate the exact time difference between two times or dates with our free online time difference calculator. Whether you need to calculate work hours, time zone differences, project durations, or schedule planning, our calculator provides accurate results instantly.
Why Use Our Time Difference Calculator?
- Multiple Formats - Supports AM/PM and 24-hour time formats
- Date & Time - Calculate differences across days, months, or years
- Detailed Breakdown - Results shown in days, hours, minutes, and seconds
- Time Zone Support - Calculate differences across time zones
- Business Hours - Exclude weekends and holidays option
- Add/Subtract Time - Add or subtract hours, minutes, seconds from any time
- Copy Results - One-click copy for easy sharing
- 100% Free - No registration or hidden fees
Common Use Cases
- Work Time Tracking - Calculate total work hours for payroll
- Project Management - Measure task durations and deadlines
- International Meetings - Schedule across time zones
- Travel Planning - Calculate flight durations and layovers
- Event Countdown - Time until birthdays, events, deadlines
- Shift Scheduling - Calculate shift lengths and breaks
- Time Logging - Track billable hours and activities
- Age Calculator - Calculate exact age or time since event
📖 How to Use
How to Use the Time Difference Calculator
Basic Time Difference
- Select the format: 12-hour (AM/PM) or 24-hour
- Enter the start time (From)
- Enter the end time (To)
- Click "Calculate" to see the difference
- Results show hours, minutes, and seconds
Date and Time Difference
- Enable "Include Date" option
- Select start date and time
- Select end date and time
- View detailed breakdown: days, hours, minutes, seconds
- See total time in different units (hours, minutes, seconds)
Add or Subtract Time
- Switch to "Add/Subtract" mode
- Enter base time/date
- Choose to add (+) or subtract (-)
- Enter duration to add/subtract
- Get the resulting time/date
Business Hours Calculation
- Enable "Business Hours Only" option
- Set working hours (e.g., 9 AM - 5 PM)
- Optionally exclude weekends
- Calculate working hours between dates
Quick Tips
- 💡 Use the current time button for quick input
- 💡 Results are shown in multiple formats
- 💡 Click copy button to copy results
- 💡 Clear button resets all fields
- 💡 Time calculations account for day crossover
⚙️ How It Works
Understanding Time Calculations
Time Difference Formula
The basic time difference is calculated by:
Difference = End Time - Start Time
When times span across midnight, the calculator automatically adds 24 hours to ensure accurate results.
Converting Time Units
- 1 hour = 60 minutes = 3,600 seconds
- 1 minute = 60 seconds
- 1 day = 24 hours = 1,440 minutes = 86,400 seconds
Time Format Conversions
12-hour to 24-hour:
- AM hours: Use as-is (12 AM = 00:00, 1 AM = 01:00)
- PM hours: Add 12 (1 PM = 13:00, 12 PM = 12:00)
24-hour to 12-hour:
- 00:00-11:59 = 12:00 AM - 11:59 AM
- 12:00-23:59 = 12:00 PM - 11:59 PM
Date Difference Calculation
For dates, the calculator:
- Converts both dates to timestamps
- Calculates the difference in seconds
- Breaks down into days, hours, minutes, seconds
- Accounts for leap years and month lengths
Real-World Examples
Example 1: Work Hours
Scenario: Calculate work hours from 9:00 AM to 5:30 PM
Calculation:
- Start: 9:00 AM (09:00)
- End: 5:30 PM (17:30)
- Difference: 8 hours 30 minutes
Example 2: Overnight Shift
Scenario: Night shift from 11:00 PM to 7:00 AM
Calculation:
- Start: 11:00 PM (23:00)
- End: 7:00 AM next day (07:00 + 24 hours)
- Difference: 8 hours
Example 3: Project Duration
Scenario: Project from Jan 15, 2024 9:00 AM to Jan 20, 2024 5:00 PM
Calculation:
- Days: 5 days 8 hours
- Total hours: 128 hours
- Total minutes: 7,680 minutes
Business Hours Calculation
When calculating business hours:
- Only count working hours (e.g., 9 AM - 5 PM)
- Exclude non-working hours
- Optionally exclude weekends
- Account for holidays if specified
Example: Friday 2 PM to Monday 10 AM (excluding weekends)
- Friday 2 PM - 5 PM = 3 hours
- Weekend = 0 hours (excluded)
- Monday 9 AM - 10 AM = 1 hour
- Total business hours = 4 hours
Time Addition/Subtraction
Adding Time:
Result = Start Time + Duration
Example: 2:30 PM + 3 hours 45 minutes = 6:15 PM
Subtracting Time:
Result = Start Time - Duration
Example: 5:00 PM - 2 hours 30 minutes = 2:30 PM
Time Zone Differences
To calculate time differences across time zones:
- Convert both times to UTC (Universal Coordinated Time)
- Calculate the difference
- Convert result back to local time if needed
Example: Meeting at 3 PM EST when it
❓ Frequently Asked Questions
How do I calculate time difference between two times?
Enter your start time and end time in either 12-hour (AM/PM) or 24-hour format. The calculator automatically computes the difference and displays it in hours, minutes, and seconds. If the end time is earlier than the start time, it assumes the end time is on the next day.
Can I calculate time difference across multiple days?
Yes! Enable the "Include Date" option to calculate time differences across days, weeks, months, or even years. Enter both the date and time for start and end points, and the calculator will show the total difference broken down into days, hours, minutes, and seconds.
How does the calculator handle overnight shifts?
The calculator automatically detects when the end time is earlier than the start time and adds 24 hours to calculate overnight durations. For example, a shift from 11 PM to 7 AM is correctly calculated as 8 hours.
What is the difference between 12-hour and 24-hour format?
12-hour format uses AM/PM (1:00 PM), while 24-hour format uses 0-23 hours (13:00). The 24-hour format is less prone to confusion and is commonly used in military, aviation, and international contexts. Both formats give the same calculation results.
Can I calculate only business hours?
Yes! Enable the "Business Hours Only" option to calculate working hours between specific times (like 9 AM to 5 PM) and optionally exclude weekends. This is perfect for calculating billable hours or project time during working days.
How do I add or subtract time from a specific time?
Switch to "Add/Subtract" mode, enter your base time, select whether to add (+) or subtract (-), then enter the duration you want to add or subtract. The calculator will show the resulting time, accounting for day changes if necessary.
Does the calculator account for time zones?
Yes, you can enable time zone support to calculate differences across different time zones. Select the time zones for your start and end times, and the calculator automatically converts and shows the accurate time difference.
How accurate are the calculations?
Our calculator is accurate down to the second. It properly handles all edge cases including midnight crossover, leap years, month-end dates, and daylight saving time transitions (when time zone support is enabled).
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💡 Quick Reference
12-Hour Format:
HH:MM AM/PM
24-Hour Format:
HH:MM (00-23)
Features:
- • Calculate time differences
- • Add/subtract durations
- • Include dates (optional)
- • Both 12 & 24-hour formats
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