Time Calculator

Add or subtract times in hours, minutes and seconds, find how long it is from one clock time to another — even across midnight — and convert any time into decimal hours or minutes. Useful for study hours, shift and overtime timesheets, travel times and maths homework on time.

First time

Hours

Minutes

min

Seconds

Second time

Hours

Minutes

min

Seconds

Result

4:06:15

4 hr 6 min 15 sec

Decimal hours

4.1042

Decimal minutes

246.25

Total seconds

14,775

Step-by-step solution

First time = 1 h 45 min 30 s = 1×3600 + 45×60 + 30 = 6,330 seconds
Second time = 2 h 20 min 45 s = 8,445 seconds
Add: 6,330 + 8,445 = 14,775 seconds
Convert back: 14,775 s = 4:06:15 (÷ 3600 for hours, remainder ÷ 60 for minutes)

How to use the time calculator

Choose a mode: add / subtract times, time between two clock times, or convert to decimal.
Add / subtract: enter hours, minutes and seconds for each time and pick + or −. Minutes and seconds above 59 are carried over.
Time between: enter a start and an end time on the 24-hour clock. If the end is earlier than the start, it is taken as the next day.
Convert: enter h:m:s to get decimal hours and minutes, or enter decimal hours (like 2.75) to get h:m:s.

Formulas

To seconds	`Total seconds = h × 3600 + m × 60 + s`
Decimal hours	`h + m ÷ 60 + s ÷ 3600` 2 h 45 min = 2 + 45/60 = 2.75 hours
Decimal → minutes	`Decimal part × 60` 1.2 hours = 1 h + 0.2 × 60 = 1 h 12 min (not 1 h 20 min)
Over midnight	`Duration = (24:00 − start) + end`

Solved examples

Example 1: Add 1 h 45 min 30 s and 2 h 20 min 45 s.

Seconds: 30 + 45 = 75 = 1 min 15 s
Minutes: 45 + 20 + 1 = 66 = 1 h 6 min
Hours: 1 + 2 + 1 = 4

Answer: 4 h 06 min 15 s

Example 2: A night shift runs from 22:30 to 06:15. How long is it?

22:30 → 24:00 = 1 h 30 min
00:00 → 06:15 = 6 h 15 min
Total = 7 h 45 min

Answer: 7 h 45 min = 7.75 hours

Example 3: Convert 1.2 hours into hours and minutes.

0.2 × 60 = 12 minutes

Answer: 1 h 12 min

Why time is not added like ordinary decimals

Time uses base 60: 60 seconds make a minute and 60 minutes make an hour. So 1:45 + 0:30 is 2:15, not 1:75 and not 2:05. Carry 60 seconds to the minutes and 60 minutes to the hours, exactly as you carry 10 in ordinary addition.

For subtraction, borrow 1 hour as 60 minutes: 3:10 − 1:45 → 2:70 − 1:45 = 1:25.

Decimal hours for timesheets

Payroll and timesheets often need hours as a decimal: 7 h 30 min = 7.5 hours, 8 h 45 min = 8.75 hours. A common mistake is to write 7 h 30 min as 7.30 — that is only 7 h 18 min. Use the convert mode to avoid it.

Frequently asked questions

How do I add hours and minutes?

Add the minutes, and if the total is 60 or more, carry 1 hour for every 60 minutes. Then add the hours. For example, 2 h 50 min + 1 h 25 min = 3 h 75 min = 4 h 15 min.

How do I calculate the time between two times that cross midnight?

Work out the time from the start to midnight, then add the time from midnight to the end. 22:30 to 06:15 = 1 h 30 min + 6 h 15 min = 7 h 45 min. The calculator does this automatically when the end time is earlier than the start.

How do I convert minutes to decimal hours?

Divide the minutes by 60. 45 minutes = 0.75 hours, 20 minutes ≈ 0.333 hours, so 3 h 20 min ≈ 3.33 hours.

What is 1.5 hours in minutes?

1.5 × 60 = 90 minutes, which is 1 hour 30 minutes.

Can the result be more than 24 hours?

Yes. When adding times, the answer can go past 24 hours; the calculator also shows it in days, hours, minutes and seconds.