Add or subtract hours and minutes from any start time, or find the exact difference between two times. Results update instantly — ideal for scheduling, time tracking, and duration calculations.
Frequently Asked Questions
How do I add time?
Enter a start time, then specify hours and minutes to add (positive values) or subtract (negative values). The result wraps correctly past midnight — for example, 23:00 + 2 hours = 01:00.
How is time difference calculated?
The difference is the absolute gap between two times on the same day. If the end time is earlier than the start time, the calculator assumes the end time is on the following day.
Does this use 12-hour or 24-hour format?
Input and output use 24-hour format. The result subtitle shows the 12-hour equivalent where helpful.
Can I calculate days between dates?
Yes. Use the Date Calculator for day-based calculations spanning multiple dates.
Is this tool free and does it work on mobile?
Yes on both counts. The Time Calculator on draft21 is completely free with no sign-up required and works on all devices.