Time Calculator
Add, subtract, and calculate time duration
Time Calculator
Add, subtract, and calculate time differences
Time Visualization
Common Time Conversions
Time in Context
How to Use the Time Calculator
This calculator helps you perform time-based calculations with hours, minutes, and seconds. You can calculate the difference between two times, add time durations together, or subtract one time from another.
Three Calculation Modes
Choose from three different calculation modes:
- Difference: Calculate the time elapsed between a start and end time (e.g., work shift duration)
- Add: Add two time durations together (e.g., combining multiple task durations)
- Subtract: Subtract one time duration from another (e.g., time remaining)
Time Units Hierarchy
Understanding how time units relate to each other
Common Use Cases
The time calculator is useful for:
- Work Hours: Calculate total hours worked in a shift
- Project Management: Track time spent on tasks and projects
- Travel Planning: Calculate journey durations and arrival times
- Cooking & Baking: Plan preparation and cooking times
- Exercise Tracking: Monitor workout durations and rest periods
- Event Scheduling: Plan event timings and durations
Typical Work Shift Timeline
Example: 9:00 AM to 5:30 PM with breaks
Understanding Time Conversions
Time is typically measured in units of seconds, minutes, hours, and days:
- 1 minute = 60 seconds
- 1 hour = 60 minutes = 3,600 seconds
- 1 day = 24 hours = 1,440 minutes = 86,400 seconds
- 1 week = 7 days = 168 hours
Quick Tips
Tips for Time Calculations
- Use 24-hour format to avoid AM/PM confusion
- For overnight calculations, add 24 hours to the end time
- Round to the nearest minute for practical planning
- Consider time zones when calculating across different locations
Time Management Strategies
Pomodoro Technique
Work in 25-minute focused sessions, followed by 5-minute breaks. After 4 sessions, take a longer 15-30 minute break. Highly effective for deep work.
Time Blocking
Schedule specific blocks of time for different tasks. For example: 9:00-11:00 deep work, 11:00-12:00 meetings, 1:00-3:00 emails. Reduces decision fatigue.
80/20 Rule
Focus 80% of your time on the 20% of tasks that produce the most results. Use this calculator to track where your time actually goes vs. where it should go.
2-Minute Rule
If a task takes less than 2 minutes, do it immediately. Use the "Add" mode to see how many 2-minute tasks fit into a 30-minute block (answer: 15!).
What Can You Do in Different Time Blocks?
- • Quick workout
- • Read 10-15 pages
- • Meditate
- • Review daily goals
- • Learn a new skill
- • Complete 2 Pomodoros
- • Write 500-1000 words
- • Attend a meeting
- • Half work day
- • Deep work session
- • Major project milestone
- • Comprehensive study
Frequently Asked Questions
How do I calculate time worked across midnight?
For shifts that span midnight, add 24 hours to the end time. For example, if you work from 10:00 PM (22:00) to 6:00 AM, enter the end time as 30:00 (24 + 6 = 30) or calculate it as two separate periods: 22:00 to 24:00 (2 hours) and 0:00 to 6:00 (6 hours), then add them together.
Can I calculate time in decimal hours?
Yes! The calculator displays total hours in decimal format in the results section. For example, 2 hours and 30 minutes is shown as 2.50 hours. This format is commonly used for payroll and billing purposes.
How accurate are the time calculations?
The calculator is accurate down to the second. All calculations properly handle carry-over between seconds, minutes, and hours. For example, 90 seconds correctly converts to 1 minute and 30 seconds.
What's the difference between add and difference mode?
Difference mode calculates the time elapsed between two specific clock times (e.g., 9:00 AM to 5:00 PM). Add mode combines two time durations (e.g., 2 hours + 3 hours). Use difference for calculating shift durations and add for combining multiple time periods.
Can I use this calculator for billing hours?
Absolutely! The calculator is perfect for tracking billable hours. Use the decimal hours display (shown in the total hours result) for invoicing. Many businesses bill in quarter-hour increments, so round to the nearest 0.25 hours (15 minutes) if needed.
How do I calculate overtime hours?
To calculate overtime, first use "Difference" mode to get your total hours worked. If you worked more than 40 hours in a week, subtract 40 hours using "Subtract" mode to find overtime hours. For daily overtime (over 8 hours), subtract 8 hours from your daily total. The decimal hours display makes it easy to multiply by your overtime rate (typically 1.5x or 2x).
How do I track breaks during a work shift?
Calculate your gross shift time with "Difference" mode (start to end time), then use "Subtract" mode to remove break time. For example: 9:00 AM to 5:30 PM = 8.5 hours, minus 30 minutes for lunch and 15 minutes for breaks = 7 hours 45 minutes of actual work time. This gives you accurate billable or payable hours.
Can this calculator help with project time estimation?
Yes! Use "Add" mode to sum up estimated time for different project tasks. For example, if Task A takes 2:30:00, Task B takes 1:45:00, and Task C takes 3:15:00, add them together to get your total project estimate of 7:30:00 (7.5 hours). The productivity breakdown shows how many work days this represents, helping with scheduling and resource planning.
How do I convert time zones for international scheduling?
For time zone conversions, use "Add" or "Subtract" mode with the time difference between zones. For example, if it's 2:00 PM in New York (EST) and you need London time (5 hours ahead), add 5 hours to get 7:00 PM GMT. For zones behind, use subtract mode. Always account for Daylight Saving Time changes, which can shift the difference by 1 hour.
What's the best way to track productivity with this calculator?
Track your "deep work" or focused time by calculating the total hours spent on high-value tasks each day. Use the Pomodoro count (shown in the results) to see how many 25-minute focus sessions your time represents. Compare your actual focused time against the "4 hours/day deep work max" shown in Quick Time Facts. The billable work value section helps you understand the dollar value of your time.
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