All Tools VerseTo convert a time to seconds, multiply the hours by 3,600, multiply the minutes by 60, and add the seconds. So 1:30:45 is 1 × 3,600 + 30 × 60 + 45 = 5,445 seconds. To go back, divide by 3,600 to get the hours, divide the remainder by 60 to get the minutes, and what is left over is the seconds.
In this guide
The formula, with examples
seconds = hours × 3600 + minutes × 60 + seconds
There are 60 seconds in a minute and 60 minutes in an hour, so one hour is 60 × 60 = 3,600 seconds.
| Time (h:mm:ss) | Working | Seconds |
|---|---|---|
| 0:01:30 | 1 × 60 + 30 | 90 |
| 0:45:00 | 45 × 60 | 2,700 |
| 1:30:45 | 3,600 + 1,800 + 45 | 5,445 |
| 2:15:30 | 7,200 + 900 + 30 | 8,130 |
| 3:59:59 | 10,800 + 3,540 + 59 | 14,399 |
| 24:00:00 | 24 × 3,600 | 86,400 |
The time to seconds converter handles all of these, plus formats like “1h 30m”, “1 hour 30 minutes”, “8.5h” and ISO 8601 durations such as PT1H30M. Paste one time per line to convert a whole list.
Seconds back to hours, minutes and seconds
Take 10,000 seconds as an example:
- Divide by 3,600. 10,000 ÷ 3,600 = 2, with 2,800 left over. That is 2 hours.
- Divide the remainder by 60. 2,800 ÷ 60 = 46, with 40 left over. That is 46 minutes.
- The last remainder is the seconds: 40.
So 10,000 seconds is 2:46:40. For more than a day, divide by 86,400 first. 100,000 seconds is 1 day with 13,600 seconds left, which is 1 day 3:46:40. On a stopwatch-style display the same value shows as 27:46:40.
The seconds to time converter does these steps for you and shows the result in several formats.
Seconds in a minute, hour, day and year
| Unit | Seconds |
|---|---|
| 1 minute | 60 |
| 1 hour | 3,600 |
| 1 day | 86,400 |
| 1 week | 604,800 |
| 30 days | 2,592,000 |
| 365 days | 31,536,000 |
One caveat for precise work: a calendar day is not always 86,400 seconds. Days with a daylight saving change are 23 or 25 hours long in local time, and leap seconds have been added to UTC in the past. For durations measured with a stopwatch, 86,400 is the right number.
Decimal hours
Timesheets often use decimal hours. Multiply by 3,600 to get seconds:
- 1.5 hours = 5,400 seconds = 1:30:00
- 2.25 hours = 8,100 seconds = 2:15:00
- 0.75 hours = 2,700 seconds = 0:45:00
- 8.5 hours = 30,600 seconds = 8:30:00
Note that 1.5 hours is 1 hour 30 minutes, not 1 hour 50 minutes. The part after the decimal point is a fraction of an hour, not a count of minutes.
Adding up several times
To add times, convert each one to seconds, add the numbers, then convert back. Here is a four-track playlist:
| Track length | Seconds | Running total |
|---|---|---|
| 3:45 | 225 | 225 |
| 4:12 | 252 | 477 |
| 2:58 | 178 | 655 |
| 5:01 | 301 | 956 |
956 seconds is 15 minutes 56 seconds. Paste the seconds column into the running total calculator to get the cumulative sum line by line.
The same method works for a time of day. 14:30:00 is 52,200 seconds since midnight. The seconds since midnight calculator shows this for the current time or any time you enter.
In Excel and Google Sheets
Spreadsheets store a time as a fraction of a day. 1:30:45 is stored as 0.0630208. Multiply by 86,400 to get seconds:
=A1*86400 time in A1 to seconds =A1/86400 seconds in A1 back to a time
Format the first result as a number. Format the second as [h]:mm:ss. The square brackets let the hours go past 24, so 100,000 seconds shows as 27:46:40 instead of wrapping to 3:46:40.
Common mistakes
- Reading “1:30” the wrong way. As minutes and seconds it is 90 seconds. As hours and minutes it is 5,400 seconds. Check which one your data uses before you convert.
- Treating decimal hours as minutes, as in the 1.5 hours example above.
- Using hh:mm:ss in a spreadsheet for long durations. Without the brackets, anything over 24 hours loses the full days.
- Forgetting to carry. 3:45 plus 4:30 is 8:15, not 7:75. Seconds over 59 roll into the next minute, which is why converting to seconds first is safer.
For timers, date calculators and more converters, see our list of the best free time and date tools.
Frequently asked questions
How many seconds are in an hour?
3,600. An hour has 60 minutes, and each minute has 60 seconds.
How do I convert minutes and seconds to seconds?
Multiply the minutes by 60 and add the seconds. A 5-kilometer run in 25:30 is 25 × 60 + 30 = 1,530 seconds, which is a pace of 306 seconds, or 5:06, per kilometer.
How many seconds are in a day?
86,400, which is 24 × 3,600. A week has 604,800.
How do I convert seconds to minutes?
Divide by 60. The whole number is the minutes and the remainder is the seconds. 445 seconds is 7 minutes 25 seconds.