Time Duration Calculator
How long between two clock times — and what time is it after adding hours and minutes? Both answers, in seconds.
Private by design: this tool runs entirely in your browser. Your files are never uploaded to a server, and nothing is stored.
Duration between two times
| Duration | — |
| In minutes | — |
Add or subtract time
| Result time | — |
How to use it
For a duration: enter the start and end clock times. Tick the overnight box if the end falls the next day.
For time maths: enter a start time, choose add or subtract, and type the hours and minutes.
Read the answer. Durations come in hours-minutes and total minutes; added times say which day they land on.
Where clock maths goes wrong
People add clock times like decimal numbers — 9:00 plus 2:30 is not 11:30 by accident, it is, but 9:45 plus 2:30 trips people up because 45 + 30 minutes is an hour and a quarter, not 75 of something. Crossing midnight is worse: a shift from 22:00 to 06:00 is 8 hours, not negative 16. This calculator keeps minutes in base 60 and days separate, so a night shift, a flight, a sleep window or a cooking time comes out right without a second thought.