Time Calculator
Instantly find the difference between two clock times, or add and subtract hours, minutes and seconds from any starting time.
Calculate Time Difference or Add/Subtract Time
Choose a mode below: find the elapsed time between two clock times, or add / subtract hours, minutes and seconds from a starting time.
Time Estimator
Work out durations and adjusted times in seconds.
How it Works
Understanding the time calculator
Pick a Mode
Choose “Time Difference” to find elapsed time between two clock times, or “Add / Subtract Time” to adjust a single time.
Enter Your Times
Use the time pickers to set your start and end times, or your starting time and the amount to add or subtract.
Handle Midnight
Tick the “next day” box for overnight spans, or let the add/subtract calculator wrap the clock automatically.
Get Your Result
See the elapsed duration in hours, minutes and seconds — or your new resulting time — instantly.
Time Unit Conversion Chart
A handy reference for converting between common units of time when working out durations by hand.
| Unit | Equivalent In Seconds | Equivalent In Minutes | Equivalent In Hours |
|---|---|---|---|
| 1 Minute | 60 seconds | 1 minute | 0.0167 hours |
| 1 Hour | 3,600 seconds | 60 minutes | 1 hour |
| 1 Day | 86,400 seconds | 1,440 minutes | 24 hours |
| 1 Week | 604,800 seconds | 10,080 minutes | 168 hours |
| Half Hour | 1,800 seconds | 30 minutes | 0.5 hours |
| Quarter Hour | 900 seconds | 15 minutes | 0.25 hours |
Time Calculator FAQ
Answers to the most frequently asked questions about calculating time differences and adding or subtracting time.
Enter a start time and an end time in hours and minutes. The calculator converts both to total minutes, subtracts the start from the end (adding 24 hours if the end time is on the next day), and displays the result as hours and minutes, plus the total in minutes and seconds.
Enter your starting time, choose Add or Subtract, then enter how many hours, minutes and seconds to apply. The calculator adjusts the clock accordingly and wraps around midnight automatically, showing whether the result lands on the next or previous day.
There are 1,440 minutes in a 24-hour day, which is also equal to 86,400 seconds. This is the figure the calculator uses when a time calculation crosses midnight into the next day.
Yes. The time fields use your browser’s native time picker, which automatically follows your device’s 12-hour or 24-hour format setting, and the calculator converts everything internally so the maths is always accurate.