⏰ Time Calculator
Time math crosses the 60-minute boundary constantly, which is why “3:45 to 6:20” is oddly hard to do in your head. This tool does it exactly, and also adds or subtracts any duration from a starting time.
If the end time is earlier than the start time, the calculator assumes it falls on the next day — useful for night shifts.
How to use this calculator
This page has two tools: one finds the duration between two times and another adds or subtracts hours and minutes from a time. Pick the card you need, then fill in its fields.
- Choose the card that matches your task: Duration between two times or Add / subtract time.
- For a duration, enter the Start time and the End time.
- For adding or subtracting, enter the Start time, the Hours, the Minutes, and the Operation (Add or Subtract).
- Read the duration or the resulting time straight from the card.
Frequently asked questions
What does the Time Calculator compute?
The duration card finds the length of time between a Start time and an End time, shown as hours and minutes plus the total in minutes. The add/subtract card takes a Start time and adds or removes a number of Hours and Minutes according to the Operation selected.
What happens when the end time is earlier than the start time?
The calculator assumes the end time is on the next day, which makes it handy for overnight shifts. A start of 22:00 and an end of 06:30 gives a duration of 8 hours 30 minutes, or 510 minutes.
Can you give a worked example?
Start time 09:00 to End time 17:30 gives 8 h 30 min, which is 510 minutes. Adding 2 Hours and 45 Minutes to 14:15 gives 17:00, and the result always wraps correctly past midnight.
What are the limits of this tool?
Both cards work on time-of-day only, not dates, so durations are capped at 24 hours. Results are exact to the minute, and the add/subtract card wraps around the clock when the result passes midnight.