How to use the time calculator
- Enter the first duration in days, hours, minutes and seconds. Empty boxes count as 0.
- Choose Add or Subtract.
- Enter the second duration and press Calculate.
You don't need to convert anything first: 90 minutes or 30 hours are fine, and the answer is tidied into days, hours, minutes and seconds.
Time units at a glance
| Unit | Equals | In seconds |
|---|---|---|
| 1 minute | 60 seconds | 60 |
| 1 hour | 60 minutes | 3,600 |
| 1 day | 24 hours | 86,400 |
| 1 week | 7 days | 604,800 |
| 1 common year | 365 days | 31,536,000 |
Minutes and seconds go up in 60s and hours in 24s, so treating times as ordinary decimals goes wrong: 1:45 + 0:30 is 2:15, but adding 1.45 + 0.30 as plain numbers gives 1.75.
How the calculator works
Each duration is turned into seconds, added or subtracted, then split back into days, hours, minutes and seconds:
\text{seconds} = 86{,}400\,d + 3{,}600\,h + 60\,m + sHow to add times by hand
- Add each unit separately: seconds with seconds, minutes with minutes, and so on.
- Carry over: every 60 seconds becomes 1 minute, every 60 minutes 1 hour, every 24 hours 1 day.
- Minutes: 45 + 30 = 75 → 1 hour carried, 15 minutes left
- Hours: 2 + 1 + 1 carried = 4
Answer: 4 hours 15 minutes (4.25 hours).
How to subtract times by hand
- Subtract from the smallest unit up.
- If a unit is too small, borrow 1 from the next unit up: 1 minute = 60 seconds, 1 hour = 60 minutes.
- 10 minutes is less than 35, so borrow 1 hour: 4 h 70 min
- Minutes: 70 − 35 = 35. Hours: 4 − 2 = 2
Answer: 2 hours 35 minutes.
Minutes to decimal hours
Timesheets and invoices often need hours as a decimal. Divide the minutes by 60:
| Minutes | Decimal hours | Minutes | Decimal hours |
|---|---|---|---|
| 5 | 0.08 | 35 | 0.58 |
| 10 | 0.17 | 40 | 0.67 |
| 15 | 0.25 | 45 | 0.75 |
| 20 | 0.33 | 50 | 0.83 |
| 25 | 0.42 | 55 | 0.92 |
| 30 | 0.50 | 60 | 1.00 |
Where a time calculator helps
- Adding up video, audio or lap times
- Totalling hours on several tasks
- Cooking and baking timers
- Flight and travel durations
- Race splits and training plans
- Billing time in decimal hours
For the time between two clock times, such as 9:00 AM to 5:30 PM, use the Hours Calculator.
Frequently asked questions
How do I add hours and minutes?
Add the minutes and the hours separately, then turn every 60 minutes into one more hour. Or enter both times above and press Calculate.
How do I convert hours and minutes to decimal hours?
Divide the minutes by 60 and add them to the hours: 2 hours 45 minutes = 2 + 45 ÷ 60 = 2.75 hours. The “In hours” line in the result does this for you.
Can I enter more than 59 minutes or 23 hours?
Yes. Any whole number works and the result is normalised, so 90 minutes becomes 1 hour 30 minutes.
Why is my result negative?
You subtracted a longer time from a shorter one. The minus sign shows how much longer the second time is.
How many seconds are in a day?
86,400 seconds: 24 hours × 60 minutes × 60 seconds.