Hours to Seconds Converter
Enter a number of hours to convert to seconds instantly. You can also include leftover minutes and seconds for a precise total. The converter works in both directions: type seconds to get hours back. A step-by-step panel shows the arithmetic, and a reference table lists common conversions from 1 to 24 hours.
Formula
Worked example
Convert 2 hours 45 minutes to seconds: 2 h x 3,600 = 7,200 s; 45 min x 60 = 2,700 s; total = 7,200 + 2,700 = 9,900 seconds (2:45:00).
How many seconds are in an hour?
There are exactly 3,600 seconds in one hour. This comes from the definition of the hour: one hour contains 60 minutes, and each minute contains 60 seconds, so 60 x 60 = 3,600. The second is the SI base unit of time, and all longer units are defined as multiples of it. The formula is simple: seconds = hours x 3,600. To go the other way, divide total seconds by 3,600 to get decimal hours.
How to convert hours, minutes and seconds together
When you have a mixed time like 1 hour 30 minutes 15 seconds, convert each part separately and then add. Multiply the hours by 3,600, the minutes by 60, then add the leftover seconds. For 1h 30m 15s: (1 x 3,600) + (30 x 60) + 15 = 3,600 + 1,800 + 15 = 5,415 seconds. This calculator does all three parts automatically when you fill in the Hours, Minutes, and Seconds fields.
Converting seconds back to hours (reverse)
To reverse the conversion, divide the total seconds by 3,600 to get decimal hours. For example, 9,000 seconds / 3,600 = 2.5 hours exactly (2 hours 30 minutes). To express the decimal remainder as minutes, take the fractional part and multiply by 60; then multiply its fractional part by 60 again for the remaining seconds. Switch the Direction field to "Seconds to Hours" and this calculator performs those steps and shows them in the panel.
Common uses for hours-to-seconds conversion
Hours-to-seconds conversion comes up in programming (Unix timestamps, sleep() calls, setTimeout(), API rate-limit windows), physics and chemistry lab calculations, sports timing and data analysis, payroll and billing (converting work hours to granular time units), and audio/video production (frame counts and buffer lengths). Knowing that 1 hour = 3,600 s, 6 hours = 21,600 s, and 24 hours = 86,400 s are the key anchors most engineers reach for.
Hours to seconds - common reference values
| Hours | Seconds | Minutes | h:mm:ss |
|---|---|---|---|
| 0.25 | 900 | 15 | 0:15:00 |
| 0.5 | 1800 | 30 | 0:30:00 |
| 1 | 3600 | 60 | 1:00:00 |
| 2 | 7200 | 120 | 2:00:00 |
| 3 | 10800 | 180 | 3:00:00 |
| 4 | 14400 | 240 | 4:00:00 |
| 5 | 18000 | 300 | 5:00:00 |
| 6 | 21600 | 360 | 6:00:00 |
| 8 | 28800 | 480 | 8:00:00 |
| 10 | 36000 | 600 | 10:00:00 |
| 12 | 43200 | 720 | 12:00:00 |
| 16 | 57600 | 960 | 16:00:00 |
| 24 | 86400 | 1440 | 24:00:00 |
Each hour contains exactly 3,600 seconds (60 minutes x 60 seconds/minute).
Frequently asked questions
How many seconds are in one hour?
Exactly 3,600 seconds. One hour = 60 minutes, and one minute = 60 seconds, so 60 x 60 = 3,600.
How do I convert 1.5 hours to seconds?
1.5 x 3,600 = 5,400 seconds. Equivalently, that is 1 hour 30 minutes = (1 x 3,600) + (30 x 60) = 3,600 + 1,800 = 5,400.
How many seconds are in 24 hours?
24 x 3,600 = 86,400 seconds. This is the number of seconds in one full day, a figure that appears frequently in programming (Unix day boundaries) and science.
How do I convert 3,600 seconds back to hours?
3,600 / 3,600 = 1 hour exactly. In general, divide any number of seconds by 3,600 to get decimal hours, then separate the decimal part into minutes and seconds if needed.
Can I convert hours and minutes together?
Yes. Fill in both the Hours and Minutes fields. The calculator multiplies hours by 3,600, minutes by 60, adds any leftover seconds, and shows the total. For example, 2 hours and 15 minutes = (2 x 3,600) + (15 x 60) = 7,200 + 900 = 8,100 seconds.
What is 0.25 hours in seconds?
0.25 x 3,600 = 900 seconds, which is exactly 15 minutes. Quarter-hour fractions are common in scheduling and billing.
How many seconds are in 8 hours?
8 x 3,600 = 28,800 seconds. A standard 8-hour workday contains 28,800 seconds, or 480 minutes.