🔢 Time & Date Duration Calculator

This calculator computes the duration between times or dates. It can calculate differences between two times (HH:MM), add or subtract a time interval (HH:MM:SS), convert seconds to time, or even calculate the total duration between two date-time values in days, hours, minutes, and seconds.

Select Operation

Enter Time (HH:MM)

Enter Second Time (HH:MM)

Enter Time Interval (HH:MM:SS)

Enter Seconds

Enter Start Date & Time

Enter End Date & Time

Result will appear here…

📌 Understanding Time & Date Calculations

This advanced calculator supports several operations:

Time Difference (Same Day): Calculates the difference between two times (HH:MM) within a single day and displays the result in HH:MM:SS format.
Add/Subtract Time Interval: Adds or subtracts a specified time interval (in HH:MM:SS) from a given time.
Time Conversion: Converts a given number of seconds into hours, minutes, and seconds (HH:MM:SS).
Date Difference: Calculates the total duration between two date-time values (using datetime-local inputs) and displays the result in days, hours, minutes, and seconds.

📌 Examples of Calculations

Operation	Example	Result
Time Difference	10:00 and 12:30	02:30:00
Add Time Interval	10:00 + 01:15:00	11:15:00
Subtract Time Interval	15:00 – 00:45:00	14:15:00
Convert Seconds	5400 seconds	01:30:00
Date Difference	2025-02-19 10:00 and 2025-02-21 12:30	2 days 02:30:00

🔧 Practical Applications

1. Scheduling: Determine meeting durations or differences between events.

2. Project Management: Adjust deadlines by adding/subtracting time intervals.

3. Reporting: Convert logged seconds into a readable format.

4. Event Planning: Calculate durations spanning multiple days.

❓ FAQs

Q1: What formats are used for inputs?
✅ Time operations use the 24-hour format (HH:MM) and intervals in HH:MM:SS, while date calculations use the datetime-local input.

Q2: How is the date difference calculated?
✅ The calculator converts the date-time values into milliseconds, computes the difference, and then converts it into days, hours, minutes, and seconds.

Q3: What if the end date is earlier than the start date?
✅ The calculator uses the absolute difference between the two date-time values.

Q4: How does it handle operations over midnight?
✅ For time-only operations, calculations assume the same 24-hour period.

Q5: How do I reset or clear all inputs?
✅ Click the “Clear” button to reset all fields and return the calculator to its default state.