Time Calculator
Work with time intervals: add durations, subtract one from another, or convert between hours, minutes, and seconds.
Last updated: August 2026 · Written and verified by Akash Pandey
Calculate with time
Total minutes
This runs the same calculation engine as the main scientific calculator, entirely in your browser. Nothing you type is sent anywhere.
Working with time
Time is base-60 (sexagesimal): 60 seconds in a minute, 60 minutes in an hour. This makes time arithmetic different from decimal math.
Conversions
| From | To | Multiply by |
|---|---|---|
| Hours | Minutes | 60 |
| Minutes | Seconds | 60 |
| Hours | Seconds | 3600 |
| Days | Hours | 24 |
| Weeks | Days | 7 |
Time zones
The world is divided into 24 standard time zones, each roughly 15° of longitude apart. Coordinated Universal Time (UTC) is the reference point. Daylight saving time shifts clocks forward by 1 hour in summer in many countries.
| City | UTC offset | DST? |
|---|---|---|
| London | UTC +0 | Yes (+1 in summer) |
| New York | UTC −5 | Yes (+1 in summer) |
| Tokyo | UTC +9 | No |
| Sydney | UTC +10 | Yes (+1 in summer) |
| Dubai | UTC +4 | No |
Worked example
Add 2 hours 30 minutes to 1 hour 45 minutes
2h 30m + 1h 45m
- Add hours:
2 + 1 = 3hours. - Add minutes:
30 + 45 = 75minutes. - 75 minutes = 1 hour 15 minutes.
- Total:
3 + 1 = 4hours,15minutes.
= 4 hours 15 minutes
- Add hours:
Frequently Asked Questions
How do I add hours and minutes?
Add the hours together and the minutes together. If the minutes exceed 60, carry over to hours (subtract 60 from minutes and add 1 to hours).
How do I convert decimal hours to hours and minutes?
Take the whole number as hours. Multiply the decimal part by 60 to get minutes. For example, 2.75 hours = 2 hours and 0.75 × 60 = 45 minutes.
How many seconds are in a day?
There are 86,400 seconds in a standard 24-hour day (24 × 60 × 60).
What is the 24-hour clock?
The 24-hour clock runs from 00:00 (midnight) to 23:59. It avoids AM/PM confusion and is used in medicine, aviation, military, and most countries worldwide.
How do I subtract times that cross midnight?
If the end time is earlier than the start time, add 24 hours to the end time before subtracting. For example, from 22:00 to 02:00 is (26:00 − 22:00) = 4 hours.
How do I convert minutes to hours?
Divide by 60. For example, 90 minutes = 90 ÷ 60 = 1.5 hours = 1 hour 30 minutes.
Why is a minute 60 seconds?
The base-60 system comes from ancient Babylonian astronomy. 60 is highly divisible (by 2, 3, 4, 5, 6, 10, 12, 15, 20, 30), making it convenient for subdivisions.
How do I calculate time duration for a project?
Enter the start and end times, then subtract. For work across multiple days, add each day's hours separately or use the hours calculator for a total across a week.